EXHIBIT 10.7
                                 LEASE AGREEMENT

      THIS LEASE is made as of this 30th day of June,  1992,  by and between (i)
Cambridge Biotech Corporation,  a Delaware corporation  qualified to do business
in the State of Maryland (the  "Landlord"),  with a business and mailing address
of 1500 East  Gude  Drive,  Rockville,  MD 20850,  and (ii) BTRL  Contracts  and
Services Inc., a Massachusetts corporation qualified to do business in the State
of Maryland (the  "Tenant"),  with a business and mailing  address of c/o Boston
Biomedica, Inc., 375 West Street, West Bridgewater, Massachusetts 02379.

                                   WITNESSETH:

      For and in  consideration  of the covenants  herein contained and upon the
terms and conditions herein set forth, the parties agree as follows:

        1.       Introductory Provisions.

                (a) Fundamental  Lease  Provisions.  Certain  Fundamental  Lease
provisions  are  presented in this Section in summary form solely to  facilitate
convenient reference by the parties hereto:


                                                                                   
                 (1)  Leased Premises             3 Taft Court                                 [See Section 2(a)
                                                  Rockville,  MD  20850                        and Exhibit A]
                 (2)  Floor Space of Leased       20,680 square  feet                          [See Section 2(a)]
                      Premises                    (more or less)

                 (3)  Gross Leasable Area of      22,680 square  feet                          [See Section 2(b))
                      Property
 
                 (4)  A. Proportionate Share      91%                                          [See Section 2(c)]
                      B. R.E. Proportionate       67%
                         Share
                      C. Insurance  Propor-       67%
                         tionate Share

                 (5)  Rent Commencement Date      July 1, 1992                                 [See Section 3(a)]

                 (6)  Expiration Data             June 30, 1997                                [See Section 3(a)]

                 (7)  Minimum Annual Rent         Lease Year           Minimum  Annual Rent    [See Section 4(a)]
                                                   1                   $19,200.00
                                                   2                   $144,760.00
                                                   3                   $206,800.00
                                                   4                   $248,160.00
                                                   5                   $289,520.00

                 (8)  Basic Monthly Rent          Lease Year           Basic Monthly Rent      [See Section 4(a)]
                                                   1                   $1,600.00
                                                   2                   $12,063.33
                                                   3                   $17,233.33
                                                   4                   $20,680.00
                                                   5                   $24,126.66

                 (9)  Tenant's  Use Clause         General  office,
                                                   research/development,                       [See Section 6]
                                                   and   manufacturing   
                                                   (as  allowed  by
                                                   zoning  code)  in  
                                                   biotechnology   and
                                                   biomedical fields

                 (10) Security Deposit             $12,063.00                                  [See Section 5]

                 (11) Leasing Broker               None                                        [See Section 35]



                (b) References and  Conflicts.  References  appearing in Section
1(a) are  intended  to  designate  some of the other  places in the Lease  where
additional provisions applicable to the particular  fundamental Lease provisions
appear.  These  references are for convenience  only and shall not be deemed all
inclusive.  Each  reference  in  this  Lease  to any of  the  fundamental  Lease
provisions  contained in Section 1(a) shall be construed to  incorporate  all of
the terms provided for under such provisions,  and such provisions shall be read
in conjunction with all other provisions of this Lease  applicable  thereto.  If
there is any conflict between any of the fundamental  Lease provisions set forth
in Section 1(a) and any other provisions of the Lease, the latter shall control.






                                       -2-





              (c) Exhibits.  The following  drawings and special  provisions are
attached hereto as exhibits and hereby made a part of this Lease:

Exhibit A.    Site Plan of Property including the Leased Premises and Adjacent 
              Laboratory Building
Exhibit B.    List of  Landlord  Repairs  After  Rent  Commencement Date
Exhibit C.    Rules and Regulations

        2.   Premises.

              (a) Leased Premises.  Landlord hereby leases to Tenant, and Tenant
hereby rents from Landlord,  that certain building (the "Leased Premises") which
is located  at 3 Taft  Court,  Rockville,  MD 20850 and is  outlined  in blue on
Exhibit A, together with the non-exclusive  right to use the common areas of the
Property as more fully described in Section 7 hereof.  The Leased Premises shall
consist of the agreed  square  footage of floor  space as  specified  in Section
l(a)(2).

              (b) The  Property.  The Leased  Premises  is a part of a parcel of
improved real property owned by Landlord  which is more fully  described as "Lot
5,  Block  A, in the  Redgate  Industrial  Park  Subdivision  as shown on a plat
thereof  recorded  in Plat Book  102,  Plat  11503  among  the Land  Records  of
Montgomery County, Maryland" (the "Property").  Landlord represents and warrants
to Tenant that it is the owner in fee simple of the Property, subject to certain
encumbrances,  rights of way, easements, and other matters of record. Located on
the Property is the Leased Premises,  a laboratory  building known as 3 1/2 Taft
Court,  Rockville,  Maryland 20850 (the  "Adjacent  Laboratory  Building"),  and
certain  common areas as  hereinafter  defined in Section 7. Landlord and Tenant
acknowledge  that the gross  leasable  area of both the Leased  Premises and the
Adjacent  Laboratory  Building is specified in Section l(a)(3) ("Gross  Leasable
Area" or "GLA"),  and shall hereafter be referred to as the GLA of the Property.
The GLA of the  Property  shall be used  hereinafter  for  purposes of computing
Tenant's  "Proportionate  Share" (as  hereinafter  defined) of certain  expenses
payable to Landlord as  "Additional  Rent" (as  hereinafter  defined).  Landlord
reserves the right to modify the GLA of the  Property,  and shall modify the GLA
of the  Property,  from  time to time  during  the  Lease  Term as a  result  of
construction of new leasable improvements or the demolition of existing leasable
improvements on the Property. Landlord's right to modify the GLA of the Property
shall not be construed to provide  Landlord  with any right to modify the GLA of
the Leased  Premises,  or to deprive Tenant of the reasonable use of any portion
of the parking areas allocated to it.

              (c) Tenant's  Proportionate Share. Tenant's Proportionate Share of
certain  expenses  hereinafter  made payable to Landlord as  Additional  Rent is
specified in Section  l(a)(4).  Said  computation is based upon the ratio of the
total area of floor space in the Leased Premises to the GLA of the Property. The
Proportionate  Share shall be  modified  during the Lease Term in the event that
the GLA of the Property is modified as described in Section 2(b) above.

        3.    Term and Acceptance by Tenant.

              (a) Lease Term.  The term of this Lease  (sometimes  herein called
the "Lease  Term")  shall  begin as of the date  specified  in Section  1(a) (5)
("Rent  Commencement  Date") and, unless sooner  terminated as herein  provided,
continue  thereafter through the date specified in Section l(a)(6)  ("Expiration
Date").  The period commencing with the Rent Commencement Date and ending on the
last day of the twelfth (12th) full calendar month  thereafter  shall constitute
the first "Lease Year" as such






                                       -3-





term is used herein.  Each  successive  full twelve (12) month period during the
Lease Term shall constitute a "Lease Year".

              (b) Acceptance of Leased  Premises.  Tenant accepts  possession of
the  Leased  Premises  in "as is"  condition,  except  that  Landlord  shall  be
obligated to complete, or cause to be completed,  repairs to the Leased Premises
which are identified in Exhibit B, in a good and workmanlike  manner using first
quality  materials,  on or before the ninetieth (90th) day following the date of
execution  of  this  Lease  by  both  parties  hereto.  Landlord  shall  use all
reasonable efforts to cause said repair work to be completed by such independent
contractors in a diligent manner. Tenant expressly  acknowledges and agrees that
Landlord has made no  representations  or warranties  with respect to the Leased
Premises,  and that no promises to alter,  repair or improve the Leased Premises
or the Property  have been made by Landlord or its agents or  employees,  unless
specifically set forth herein.

              (c)  Permits.  Tenant  shall  be  responsible  for  obtaining  the
occupancy permit (if and to the extent required by law) and all other permits or
licenses  necessary  for its  lawful  occupancy  of the  Leased  Premises.  This
requirement shall not relieve Tenant of its liability for the payment of Minimum
Annual Rent and Additional  Rent, and the  performance of all other  obligations
contained herein,  from and after the Rent Commencement  Date, in the event that
all of said  approvals,  permits  and  licenses  have  not been  acquired  prior
thereto.

        4.  Rent.

              (a)  Minimum   Annual  Rent.  The  Minimum  Annual  Rent  reserved
hereunder in Section  1(a)(7) shall be payable by Tenant to Landlord during each
Lease Year of the Lease Term in equal monthly installments of Basic Monthly Rent
in the amounts set forth in Section 1(a)(8),  due in advance,  without notice or
demand, and without set-off, deduction,  recoupment or abatement of any kind, on
the Rent  Commencement  Date and the first (1st) day of each and every  calendar
month thereafter  during the Lease Term. In the event that the Rent Commencement
Date  occurs on a day other than the first day of a calendar  month or the Lease
Term ends on a day other than the last day of a calendar  month,  then the Basic
Monthly Rent or Additional Rent for such partial month(s) shall be computed on a
per diem basis by dividing the Basic Monthly Rent or  Additional  Rent by thirty
(30) and  multiplying  it by the number of days in the partial  calendar  month.
Rent shall be paid to  Landlord,  or to such other  person(s),  or at such other
address as Landlord may designate to Tenant from time to time.

              (b) Additional Rent.

                    (i)  General.  Whenever  it is provided by the terms of this
Lease that  Tenant is  required  to make any  payment to  Landlord  other than a
payment of Minimum Annual Rent,  such payment shall be deemed to be a payment of
additional  rent  ("Additional  Rent").  Unless  otherwise  expressly  specified
herein,  Additional  Rent shall be paid by Tenant with the next  installment  of
Basic Monthly Rent thereafter  falling due.  Additional Rent shall include,  but
not be limited to:

                    (ii) Real  Estate  Taxes.  On or before  September  1, 1992,
Tenant  shall pay to Landlord  its R.E.  Proportionate  Share of the Real Estate
Taxes to be incurred by Landlord on the Property  during the 1992-1993 tax year,
based upon a copy of the 1992-1993 tax bill for the Property delivered to Tenant
by Landlord  prior  thereto (or if a copy of said tax bill is not  delivered  to
Tenant until after  September 1, 1992, then within five (5) business days of the
receipt thereof).  Commencing upon the 1st day of October,  1992, and thereafter
on the first day of each calendar month throughout the Lease Term,  Tenant shall
pay to Landlord, without





                                      -4-






notice or demand therefor  (other than the annual notice of Landlord's  estimate
of Tenant's R.E.  Proportionate Share of the Real Estate Taxes and a copy of the
tax bill as described in the following  paragraph of this Section),  and without
any deduction whatsoever,  one-twelfth (1/12) of its R.E. Proportionate Share of
Landlord's  good faith  estimate  of the Real  Estate  Taxes to be  incurred  by
Landlord on the Property during the following tax year (prorated,  if necessary,
if the  remainder  of the Lease Term  constitutes  less than the full tax year).
Tenant's obligation to pay its R.E. Proportionate Share of the Real Estate Taxes
incurred during the Lease Term shall survive the expiration or other termination
of the Lease.

              The term "Real Estate Taxes" shall mean all taxes and assessments,
general and special, ordinary and extraordinary, foreseen and unforeseen, now or
hereafter assessed, levied or imposed upon the Property, including both the land
and the improvements  which are built thereon,  including,  without  limitation,
front foot benefit charges and adequate  public facility costs and  assessments,
together with (i) any tax,  assessment,  or other  imposition in the nature of a
real estate tax, (ii) any ad valorem tax on rent or any tax on income if imposed
in lieu of or in addition to real estate  taxes and  assessments,  and (iii) any
taxes and assessments  which may hereafter be substituted for real estate taxes,
including by way of illustration  only, any tax,  assessment or other imposition
(whether a business  rental or other tax) now or hereafter  levied upon Landlord
for a tenant's use or occupancy of or conduct of business on the Property,  or a
tenant's  improvements  to or furniture,  fixtures or equipment on the Property.
Real Estate Taxes shall also include all  reasonable  costs incurred by Landlord
in contesting the validity or amount of any such taxes.  Real Estate Taxes shall
not  include  transfer,  inheritance,  capital  stock or  income  taxes or other
similar personal tax of Landlord,  nor any late charges,  penalties or interest,
incurred due to untimely payments by Landlord in connection with said tax.

              Within fifteen (15) days after Landlord's  receipt from the taxing
authority  of the Real  Estate Tax bill for the  1993-1994 tax year and for each
tax year  thereafter  during the Lease Term,  Landlord shall deliver to Tenant a
copy  of  such  tax  bill,  together  with a  statement  showing  Tenant's  R.E.
Proportionate  Share of the actual Real  Estate  Taxes due for said tax year and
the amount of payments  made by Tenant based upon the estimate  thereof.  Tenant
shall  pay  Landlord,  within  thirty  (30)  days of  Tenant's  receipt  of such
statement,  Tenant's R.E. Proportionate Share of the excess, if any, of the Real
Estate Taxes for such tax year over the estimated  costs thereof.  If the amount
paid by Tenant as Tenant's R.E. Proportionate Share of the estimated Real Estate
Taxes for such tax year  exceeded  Tenant's R.E.  Proportionate  Share of actual
Real Estate Taxes for such tax year, the excess shall be credited toward payment
of the next  installment of Basic Monthly Rent to be paid by Tenant after Tenant
receives said statement from Landlord. If the amount paid by Tenant for the last
tax year of the Lease Term exceeds Tenant's R.E.  Proportionate  Share of actual
Real Estate Taxes for such tax year, Landlord shall pay Tenant the excess amount
within thirty (30) days after  Landlord's  submission to Tenant of the aforesaid
statement for such tax year.

             In the event that the Adjacent  Laboratory  Building is  demolished
during  the  Lease  Term,  then,  commencing  upon  the  effective  date  of the
reassessment of the Property and the modification of Real Estate Taxes resulting
from such  demolition,  and for so long as the Leased  Premises  constitutes one
hundred  percent  (100%) of the leasable  improvements  located on the Property,
Tenant shall be obligated to pay Tenant's R.E.  Proportionate  Share of the Real
Estate Taxes assessed  against the Property land and one hundred  percent (100%)
of the Real Estate Taxes assessed against the Property improvements.





                                       -5-





         Upon Tenant's  written  request,  Landlord  will  contest,  at Tenant's
expense,  the  validity or amount of any such Real Estate Tax.  Tenant  shall be
entitled to its R.E. Proportionate Share of any refund.

         Landlord   shall  deposit  and   thereafter   hold  in  escrow,   until
disbursement,  the funds  received  from Tenant  pursuant to this  section in an
interest bearing, federally insured account. All interest earned on said account
shall be  credited  to Tenant and shall be used in the  adjustments  to Tenant's
payments made hereunder from time to time during the Lease Term so that Landlord
collects only such monies as are  necessary to pay Tenant's  R.E.  Proportionate
Share of said Real Estate Taxes.

         In  addition  to  Tenant's  obligation  for  the  payment  of its  R.E.
Proportionate  Share of the Real Estate  Taxes,  Tenant shall be liable for, and
shall pay before delinquency,  all taxes levied against any personal property or
trade fixtures placed by Tenant in or about the Leased Premises.

         (iii)  Insurance.  Commencing  upon  the  Rent  Commencement  Date  and
thereafter  throughout  the Lease Term,  Tenant  shall pay to  Landlord  without
notice or demand  therefor and without any deduction  whatsoever,  its Insurance
Proportionate  Share of the premium  cost of the casualty  insurance,  liability
insurance,  rent loss  insurance,  and other  reasonable  and necessary  form of
insurance  carried by Landlord with respect to the Property  ("Insurance  Cost")
during any policy  year;  provided,  however,  that if the  Adjacent  Laboratory
Building  is  demolished  during  the  Lease  Term,  then  commencing  upon such
demolition  and for so long  as the  Leased  Premises  constitutes  one  hundred
percent  (100%) of the leasable  improvements  on the Property,  Tenant shall be
obligated to pay one hundred percent (100%) of the Insurance Cost.

        Not less than ten (10) days before the Rent Commencement Date,  Landlord
shall deliver to Tenant a written statement of Landlord's estimate of the amount
of the Insurance Cost for the then-current  policy year, and Tenant's  Insurance
Proportionate  Share of such Insurance Cost. On the Rent Commencement  Date, and
on the first day of each month  thereafter  throughout  the Lease  Term,  Tenant
shall  pay  one-twelfth  (1/12) of  Tenant's  Insurance  Proportionate  Share of
Landlord's  estimate of the Insurance Cost for the then-current  policy year, as
shown  on  Landlord's  estimate.  Landlord  shall  submit  its  estimate  of the
Insurance  Cost  for  the  forthcoming   policy  year  and  Tenant's   Insurance
Proportionate  Share thereof at the  commencement  of each such policy year, and
Tenant's  monthly  payments made after its receipt of such estimate  shall be in
the  amount  of  one-twelfth   (1/12)  of  the  amount  of  Tenant's   Insurance
Proportionate  Share of Insurance Cost as shown on such  estimate.  Landlord may
revise its  estimate of the  Insurance  Cost at any time during a policy year by
notice to Tenant,  setting  forth such revised  estimate and Tenant's  Insurance
Proportionate  Share thereof. In such event, all monthly payments made by Tenant
after such notice shall be in an amount  calculated on the basis of such revised
estimate.  Tenant  shall,  in all cases,  continue to make  monthly  payments of
Insurance  Cost  based on the last  estimate  received  from  Landlord  until it
receives a revised or updated estimate.

        After the end of each policy year,  Landlord will as soon as practicable
submit to Tenant a statement of the actual  Insurance  Cost for such policy year
and Tenant's  Insurance  Proportionate  Share thereof.  Landlord shall cause its
insurance carrier,  whenever practical,  to issue policies of insurance covering
the Leased  Premises  which are separate and apart from the Adjacent  Laboratory
Building and all other  properties  owned by Landlord,  in which event  Tenant's
Proportionate Share of Insurance Cost shall be the full cost payable pursuant to
said





                                       -6-




separate  policy.  Where such separate  policies  cannot be issued  practically,
Landlord  shall  cause its  insurance  carrier  to  provide a written  statement
identifying  the manner in which all premiums  paid by Landlord are allocated to
reflect the portion thereof  attributable to the insurance carried on the Leased
Premises and the portion thereof  attributable  to the insurance  carried on the
Adjacent  Laboratory  Building and other  properties  owned by Landlord.  Tenant
shall  pay  Landlord,  within  thirty  (30)  days of  Tenant's  receipt  of such
statement,  Tenant's  Insurance  Proportionate  Share of the excess,  if any, of
Insurance  Cost for such policy year over the projected  Insurance  Cost. If the
amount paid by Tenant as Tenant's Insurance Proportionate Share of the estimated
Insurance Cost for such policy year exceeded  Tenant's  Insurance  Proportionate
Share of  actual  Insurance  Cost for such  policy  year,  the  excess  shall be
credited toward payment of the next installment of Basic Monthly Rent to be paid
by Tenant after Tenant receives said statement from Landlord. If the amount paid
by Tenant for the last policy year of the Lease Term exceeds Tenant's  Insurance
Proportionate  Share of actual Insurance Cost for such year,  Landlord shall pay
Tenant the excess amount within thirty (30) days after Landlord's  submission to
Tenant of the aforesaid Insurance Cost statement for such policy year.

        Landlord   shall   deposit  and   thereafter   hold  in  escrow,   until
disbursement,  the funds  received  from Tenant  pursuant to this  section in an
interest bearing, federally insured account. All interest earned on said account
shall be  credited  to Tenant and shall be used in the  adjustments  to Tenant's
payments made hereunder from time to time during the Lease Term so that Landlord
collects  only  such  monies  as  are   necessary  to  pay  Tenant's   Insurance
Proportionate Share of said Insurance Cost.

        Landlord agrees that, at all times during the Lease Term, it shall carry
casualty  insurance  and  liability  insurance  in such form and in such amounts
which are consistent  with and comparable to the coverage of casualty  insurance
policies  and  liability   insurance   policies  carried  by  landlord's  owning
commercial buildings located in Montgomery County,  Maryland that are similar to
the Leased Premises.

                   (iv) Utility Expenses Not Separately Metered.

                         (aa) Throughout the Lease Term, Tenant agrees to pay to
Landlord,  as Additional Rent,  Tenant's  Proportionate Share of all water usage
charges,  exterior  electric  lighting  charges,  and any other utility  charges
("Shared  Charges") not separately  metered (and only for so long as each is not
separately  metered) for each of the Leased  Premises,  the Adjacent  Laboratory
Building, and the common areas of the Property.

                         (bb) Upon receipt of each  billing for Shared  Charges,
Landlord  will as soon as  practicable  submit to Tenant a  statement  of Shared
Charges  incurred for the preceding  billing period.  Tenant shall pay Landlord,
within  thirty  (30)  days  of  Tenant's  receipt  of such  statement,  Tenant's
Proportionate Share of Shared Charges.

                   (v)  Landlord's  Enforcement  Costs.  Additional  Rent  shall
include  any  and  all  expenses  incurred  by  Landlord,  including  reasonable
attorneys'  fees,  for  the  collection  of  monies  due  from  Tenant  and  the
enforcement of Tenant's  obligations  under the provisions of this Lease. In the
event  Minimum  Annual Rent or Additional  Rent is not paid within  fifteen (15)
business days of its due date,  Landlord,  at its sole option, may assess a late
charge equal to five percent (5%) of the amount of the delinquent  Basic Monthly
Rent and Additional Rent as compensation for the additional administrative costs
incurred by Landlord as a result of such late payment.






                                       -7-




                         (c)  Payment  of  Rent.  Any  Minimum  Annual  Rent  or
Additional  Rent which is not paid within five (5) business  days after the same
is due shall bear interest  ("Penalty  Rate") at one percentage (1%) point above
the prime rate of interest by  NationsBank/Maryland  existing  from time to time
and adjusted  each day the prime rate is  redetermined  to reflect the change in
said  prime  rate of  interest,  from the due date  until the date  received  by
Landlord.  Any payments of Minimum  Annual Rent or Additional  Rent by Tenant or
acceptance  by  Landlord  of a lesser  amount  than shall be due from  Tenant to
Landlord shall be treated as a payment on account. The acceptance by Landlord of
a check for a lesser amount with an  endorsement or statement  thereon,  or upon
any letter  accompanying such check, that such lesser amount is payment in full,
shall be given no effect,  and Landlord may accept such check without  prejudice
to any other  rights or remedies  which  Landlord may have  against  Tenant.  If
Landlord  receives  from Tenant two (2) returned or "bounced"  checks in any one
Lease Year,  Landlord  may require all future  Rent by  cashier's  or  certified
check.

             5.      Security Deposit.

                         (a) Contemporaneously with the execution of this Lease,
Tenant has deposited with Landlord the sum specified in Section  1(a)(10) as the
security  deposit  ("Security   Deposit"),   the  receipt  of  which  is  hereby
acknowledged.  Said  Security  Deposit  shall serve as security for the faithful
performance  by Tenant of all the terms,  covenants and conditions of this Lease
to be kept and performed by Tenant during the Lease Term. If, at any time during
the Lease Term,  any payment of Minimum  Annual Rent or  Additional  Rent herein
reserved  shall be  overdue  and  unpaid,  then  Landlord  may,  at its  option,
appropriate and apply any portion of said Security Deposit to the payment of any
such overdue rent or other sum.

                         (b) In the event of the  failure  of Tenant to keep and
perform any of the terms,  covenants and conditions of this Lease to be kept and
performed by Tenant, then Landlord, at its option, may appropriate and apply the
entire Security Deposit,  or so much thereof as may be necessary,  to compensate
Landlord for loss or damage sustained or suffered by Landlord due to such breach
on the part of Tenant.  Should  the  entire  Security  Deposit,  or any  portion
thereof, be appropriated and applied by Landlord for the payment of overdue rent
or other sums due and  payable to  Landlord  by Tenant  hereunder,  then  Tenant
shall,  upon the  written  demand of  Landlord,  forthwith  remit to  Landlord a
sufficient  amount in cash to restore the Security  Deposit to the original sum.
Tenant's  failure  to do so within  five (5) days after  receipt of such  demand
shall  constitute a breach of this Lease.  Should Tenant comply with all of said
terms,  covenants  and  conditions  of this Lease and  promptly  pay all Minimum
Annual  Rent and  Additional  Rent  herein  provided  as it falls due,  then the
Security Deposit (and all accrued  interest) shall be returned in full to Tenant
within forty-five (45) days of the Expiration Date or earlier termination of the
Lease Term.

                         (c)  Landlord   shall   deliver  the  funds   deposited
hereunder  by  Tenant as a  Security  Deposit  to the  purchaser  of  Landlord's
interest  in the  Property  and/or  the Leased  Premises  in the event that such
interest is sold, and thereupon  Landlord  shall be discharged  from any further
liability with respect to such Security Deposit.

                         (d) If the  Tenant  fails  to  take  possession  of the
Leased  Premises as required by this Lease,  the Security  Deposit  shall not be
deemed liquidated  damages,  and Landlord's use of the Security Deposit pursuant
to this Section 5 shall not preclude  Landlord from  recovering  from Tenant all
additional damages incurred by Landlord.





                                       -8-





                         (e)  Landlord  shall  deposit  the funds  delivered  by
Tenant as a Security Deposit in an interest bearing,  federally insured account,
and shall  hold the  Security  Deposit in such an  account(s)  during the entire
Lease  Term.  For so long as Signet  Bank/Maryland  holds a first lien  security
interest in the  Property,  the Security  Deposit shall be held in an account at
Signet  Bank/Maryland which identifies Landlord as the escrow agent or custodian
of the proceeds constituting the Security Deposit for the benefit of Tenant. All
interest  earned on said  account  shall be credited to Tenant,  and, so long as
Tenant is not in default of its obligations under this Lease, Landlord shall pay
to Tenant  all  accrued  interest  (and shall  deliver to Tenant an  appropriate
statement showing the accrual of such interest on said account) on or before the
31st day of  January  of each  calendar  year  during  the  Lease  Term.  Tenant
acknowledges that its tax  identification  number is #04-3152484 for purposes of
reporting to the Internal Revenue Service interest earned on said account.

             6.       Use.

                         (a) Use.  Tenant shall use the Leased  Premises for the
purposes specified in Section 1(a)(9), and for no other purpose.

                         (b) Compliance With Laws, Fire Insurance,  Condition of
Leased  Premises.  Tenant  shall not do, or  permit  anything  to be done in the
Leased  Premises or on the Property,  or bring or keep anything  therein,  which
will in any way  invalidate  or  conflict  with fire  insurance  policies on the
Property,  including,  but  not  limited  to all  improvements,  the  Property's
fixtures and personal  property kept therein,  or obstruct or interfere with the
rights of the Landlord or of other tenants of the Property,  or in any other way
injure or annoy  Landlord  or such other  tenants,  or subject  Landlord  to any
liability  for injury to persons or damage to property,  or  interfere  with the
good order of the Property,  as  determined  by Landlord in its sole  reasonable
discretion.  Tenant  shall  refrain or  discontinue  said use  immediately  upon
receipt of written notice from Landlord  requiring such action.  Tenant,  at its
expense,  shall comply with all present and future laws, rules or regulations of
any federal,  state or municipal  authority,  or the Maryland Fire  Underwriters
Rating  Bureau,  or with any notice  from any  public  officer  pursuant  to law
pertaining  to Tenant's  occupancy or use of the Leased  Premises,  whether such
notice shall be served on Landlord or Tenant  (including,  where necessary,  the
construction of capital  improvements to the Leased Premises).  Tenant agrees to
indemnify,  defend, and hold Landlord harmless from all liability, damage, cost,
and expense (including, without limitation, court costs and reasonable attorneys
fees) resulting from any injury to persons or damage to property occurring in or
around the Leased Premises, whether occasioned by any act or omission of Tenant,
Tenant's agents, contractors, servants, employees, invitees or licensees. Tenant
agrees that any increases of fire insurance  premiums on the Leased  Premises or
contents caused by the occupancy of Tenant and any expenses or costs incurred in
consequence  of  negligence  or  carelessness  or the willful  action of Tenant,
Tenant's employees, agents, contractors,  servants, invitees, or licensees shall
be deemed Additional Rent and paid by Tenant to Landlord as they accrue.

            7.   Common Areas.

                    (a) Common  Areas  Defined.  In this Lease,  "common  areas"
means all areas, facilities and improvements provided, from time to time, on the
Property for the mutual convenience and use of all tenants or other occupants of
the Leased  Premises  and the Adjacent  Laboratory  Building,  their  respective
agents,  employees,  and invitees,  and shall include, if provided,  but are not
limited to, parking areas and facilities, access roads,




                                       -9-




driveways,  retaining walls, sidewalks, walkways, landscaped areas, and exterior
lighting facilities.

              (b) Landlord's  Control.  Landlord shall, as between  Landlord and
Tenant, at all times during the Lease Term have the sole and exclusive  control,
management and direction of the common areas, and may, at any time and from time
to time  during the Lease  Term,  exclude  and  restrain  any person from use or
occupancy thereof, excepting,  however, Tenant and other tenants of Landlord and
bona fide invitees of either who make use of said areas in  accordance  with the
rules and  regulations  established  by Landlord  from time to time with respect
thereto.  The rights of Tenant in and to the common  areas shall at all times be
subject to the rights of others to use the same in common  with  Tenant,  and it
shall be the duty of  Tenant  to keep all of said  areas  free and  clear of any
obstructions   created  or  permitted  by  Tenant  or  resulting  from  Tenant's
operation.  Landlord  may at any time and from time to time (i) close all or any
portion of the common  areas to make  repairs or changes,  (ii) close all or any
portion of the common  areas to such extent as may, in the opinion of  Landlord,
be necessary to prevent a dedication thereof or the accrual of any rights to any
person or to the public therein, and (iii) do and perform such other acts in and
to said areas as, in the  exercise of good  business  judgment,  Landlord  shall
determine to be advisable with a view to the  improvement of the convenience and
use thereof by tenants, their employees, agents, and invitees. Landlord shall at
all times have the right and privilege of  determining  the nature and extent of
the common  areas,  and of making such  changes,  rearrangements,  additions  or
reductions therein and thereto from time to time which in its opinion are deemed
to be desirable  and for the best interest of all persons using the common areas
or which are as a result of any federal, state or local environmental protection
or other law, rule, regulation, guideline or order. The purpose of the site plan
attached hereto as Exhibit A is to show the approximate locational  relationship
of the Leased  Premises to the  Adjacent  Laboratory  Building and to the common
areas as of the Rent  Commencement  Date.  Nothing  described in Exhibit A shall
limit or  prevent  Landlord  from  effecting  any  change or  alteration  to the
Property as described in this paragraph. Nothing contained in this Section shall
give Landlord the right to impose  restrictions  on the use and enjoyment of the
common areas by Tenant,  or to make  modifications to the common areas, in a way
to cause Tenant to be unable to use the Leased  Premises and the common areas in
a reasonable manner for the purposes originally contemplated by this Lease.

                         (c) Parking Spaces. During the Lease Term, Tenant shall
have the exclusive right to the use of all parking spaces in the common areas of
the Property,  except for the six (6) parking  spaces which are marked in red on
Exhibit A and are reserved by Landlord for its use.

        8. Rules and  Regulations.  Tenant agrees to comply with and observe any
reasonable rules and regulations promulgated by Landlord as set forth in Exhibit
C, which may be supplemented or amended from time to time by Landlord.  Tenant's
failure to keep and observe said rules and regulations shall constitute a breach
of the terms of this  Lease in the same  manner  as if the same  were  contained
herein as covenants.

        9. Utilities.  Tenant shall be solely responsible for and shall promptly
pay any and all utility charges including but not limited to electricity,  fuel,
gas, and  telephone  (including  equipment  and  installation  charges) used in,
consumed  at, or  supplied  to the Leased  Premises.  Tenant  shall  immediately
transfer all separately  metered  utility  accounts for the Leased Premises into
its own name on the Rent  Commencement  Date.  Tenant shall pay to Landlord,  as
Additional  Rent,  its  Proportionate  Share of any and all  bills  for  utility
charges which are not




                                      -10-




separately metered in the manner described in Section 4(b)(iv) hereof.

        10. Landlord's Right of Entry.  Landlord, and its agents, shall have the
right, upon prior notice to Tenant and during  reasonable  business hours during
the Lease Term (except in the case of an emergency involving damage to person or
property),  to enter upon the Leased  Premises to examine  the same,  or to make
such repairs,  alterations  or  improvements,  as Landlord may deem necessary or
proper,  or to remove any alteration or improvement which is in violation of the
provisions  of this  Lease,  provided,  however,  Landlord  shall not  adversely
interfere  with  Tenant's  business  operations in a material  manner.  Landlord
reserves the right to show the Leased Premises to prospective tenants or brokers
during  the last  ninety  (90) days of the Lease  Term,  and to show the  Leased
Premises to prospective  purchasers at all reasonable times, provided that prior
verbal  notice  is given to  Tenant  in each  case  and  that  Tenant's  use and
occupancy of the Leased Premises shall not be materially  inconvenienced  by any
such action of Landlord.

        11.   Condition - Maintenance and Repair.

                         (a) Tenant's Responsibility.  Tenant shall maintain the
Leased Premises in  substantially  the same good order and condition as it is on
the  commencement  of the Lease Term and shall  return the  Leased  Premises  to
Landlord in such condition at the Expiration Date or at the earlier  termination
of this Lease, ordinary wear and tear excepted.  Except as obligations to repair
are expressly  delegated to Landlord as described in Section 11(b) below, Tenant
shall be responsible  for the full cost of all maintenance and repair of (i) the
Leased Premises,  including but not limited to the doors,  door jambs,  windows,
window  casings and sills,  screens,  floor  coverings,  walls  (excluding  load
bearing structures), and ceilings located in the Leased Premises, and all pipes,
gutters, downspouts, wires, conduits and other equipment and fixtures located in
the Leased  Premises,  and (ii) the common areas of the Property  (including all
landscaping  thereon,  except for the  landscaping  immediately  surrounding the
Adjacent  Laboratory  Building).  Tenant, at its expense,  shall perform routine
maintenance,  repair,  and  replacement  of the plumbing,  electrical,  heating,
ventilating and  air-conditioning  systems, and all other systems and equipment,
serving the Leased  Premises.  Tenant will  throughout the Lease Term obtain and
keep in  force a  maintenance  contract  with a  qualified  service  company  to
regularly inspect and perform maintenance  services to the heating,  ventilating
and air-conditioning system serving the Leased Premises. Tenant, at its expense,
shall furnish Landlord with a copy of said maintenance contract, and of renewals
or replacements thereof,  promptly after the effective date thereof. All repairs
and maintenance  required to be performed by Tenant at the Leased Premises shall
be made or performed  within a reasonable  period of time upon the occurrence of
the necessity therefor,  and shall be made or performed in a workmanlike manner,
using first  class  materials,  by a  contractor  duly  licensed in the State of
Maryland,  and shall be made or performed in accordance  with (i) all applicable
federal, state and county governmental codes and regulations, and (ii) insurance
requirements.  Tenant shall also be  responsible  for keeping all  sidewalks and
parking areas on the Property free and clear of dirt, trash,  debris, ice, snow,
and any other obstructions;  provided, however, that Landlord shall upon request
promptly  reimburse  Tenant  for  nine  percent  (9%) of the  cost  of any  such
services.  Tenant shall keep its trash and garbage in enclosed  containers  in a
trash holding area within the Leased  Premises,  and shall perform regular trash
removal from such trash holding area.  Tenant shall also be responsible  for the
performance of regular,  periodic pest control  services at the Leased Premises.
All  glass,  both  exterior  and  interior,  shall be  maintained  in the Leased
Premises at the sole





                                      -11-




risk of Tenant,  and Tenant  agrees to replace  any glass  promptly  at its sole
expense in the event of breakage.

                         (b)   Landlord's   Responsibility.   Except   for   any
structural  alterations or improvements made by Tenant,  Landlord shall maintain
in good order and repair the roof and the structural portions of the foundation,
floors,  stairwells,  exterior walls, columns and other load bearing elements of
the Leased Premises, and shall perform all non-routine repair and replacement of
the heating,  ventilating and  air-conditioning  system at the Leased  Premises,
provided,  in each case, that Tenant shall give Landlord notice of the necessity
therefor, whereupon Landlord shall have a reasonable period of time within which
to make such repairs, and provided,  further, that any such repairs necessitated
by the acts or  omissions  of Tenant,  its  agents,  employees,  contractors  or
invitees,  shall be performed at Tenant's expense, and the cost thereof shall be
paid by Tenant to Landlord,  as Additional  Rent,  within twenty (20) days after
Landlord's submission of a bill therefor.

        12.  Alterations  or  Improvements  by  Tenant.  Except  for  incidental
painting and  decoration of the interior of the Leased  Premises and other minor
alterations  and  improvements  which do not  affect  the  structure  or utility
systems  of  the  Leased  Premises,  Tenant  shall  not  make  any  alterations,
additions,   or   improvements,    structural   or   otherwise    (collectively,
"Alterations")  in, on or to the  Leased  Premises,  without  the prior  written
consent  of  Landlord,  which  consent  shall not be  unreasonably  withheld  or
delayed.  In connection with Landlord's  review of such proposed  alterations or
improvements prior to giving its consent thereto,  Landlord shall have the right
to require  that Tenant  supply  plans,  specifications,  working  drawings  and
similar  documents  in  reasonable  detail  which  show the  scope of work to be
performed  within  the  Leased  Premises.  Landlord's  approval  of  the  plans,
specifications  and working  drawings for Tenant's  alterations and improvements
shall create no liability on the part of Landlord for their completeness, design
sufficiency,  or compliance  with all laws,  rules,  regulations of governmental
agencies or authorities. Landlord acknowledges that Tenant desires to build a P3
laboratory in the Leased Premises during the Lease Term, and that Landlord shall
not unreasonably  withhold or delay its consent to the construction thereof. Any
contractors  employed by Tenant to perform  Tenant's work (i) shall be qualified
to  perform  such work and  licensed  in the State of  Maryland  and (ii)  shall
maintain any insurance which may be reasonably  required by Landlord,  and (iii)
shall be bonded or otherwise  reasonably  satisfactory to Landlord.  Tenant will
defend,  indemnify  and hold  Landlord  harmless  from and  against  any and all
expenses,  liens,  claims or damages,  including  attorneys' fees, for injury to
person or property which may or might arise,  directly or indirectly,  by reason
of the making of any  Alterations.  If any Alterations are effected  without the
prior written  consent of Landlord,  Landlord may remove or correct the same and
Tenant shall be liable for any and all  expenses of this work.  All rights given
to Landlord herein shall be in addition to any other right or remedy of Landlord
contained  in  this  Lease.  Tenant  shall  be  obligated  to  make  any and all
Alterations and other improvements to the Leased Premises required by applicable
federal, state, and local law, in connection with the use of the Leased Premises
by Tenant during the Leased Term. Tenant hereby agrees that all Alterations made
in, to, or on the Leased Premises shall,  unless  otherwise  provided by written
agreement or by the provisions of Section 13 below,  be the property of Landlord
and  shall  remain  upon and be  surrendered  with the  Leased  Premises  on the
Expiration Date or other termination of this Lease.

         13.  Surrender.  Upon the Expiration  Date or other  termination of the
Lease Term,  Tenant shall quit and surrender the Leased Premises to the Landlord
in good order and condition,




                                      -12-




ordinary  wear and tear  excepted,  and Tenant  shall remove all of its personal
property  from the Leased  Premises  on or before the  Expiration  Date or other
termination  of this  Lease.  Tenant's  obligation  to observe  or  perform  the
covenants  described in this Section 13 shall  survive the  expiration  or other
termination of this Lease. If Tenant does not remove Tenant's  furniture,  trade
fixtures and all other items of personal  property of every kind and description
from the Leased Premises as specified  herein,  then Landlord shall be permitted
to remove, dispose or otherwise discard such property without further payment or
credit by Landlord to Tenant. Notwithstanding anything to the contrary contained
in this Lease,  Tenant  shall have the right and the  obligation , at the end of
the Lease  Term,  to remove all  built-in  desks,  cabinets,  basins,  emergency
showers and other pieces of equipment  which are affixed to the Leased  Premises
by Tenant.  In connection  with the removal of said  equipment,  Tenant shall be
obligated to stub pipes;  bundle and cap wires; close ducts;  repair and replace
(as appropriate)  flooring coverings;  repair,  replace,  finish and repaint (as
appropriate)  walls,  and  perform  all other acts which are  necessary  for the
Leased  Premises to be returned to Landlord in same good order and  condition as
exists of the Rent Commencement Date.

        14.  Tenant  Holding  Over.  If Tenant  holds  possession  of the Leased
Premises after the Expiration Date or other termination of this Lease,  Landlord
shall have the option,  exercisable in writing within thirty (30) days after the
date of  termination  as  aforesaid,  to treat Tenant as a  trespasser,  or as a
tenant by the month. If the Landlord fails to make such election then the Tenant
shall be deemed a tenant by the month,  commencing  with the first day after the
termination  of the  Lease at one  hundred  fifty  percent  (150%)  of the Basic
Monthly  Rent paid  during  the last month of the Lease  Term,  and upon all the
other  terms of this Lease,  including  the  provisions  of this  Section.  Said
holdover term shall terminate upon thirty (30) days notice from one party to the
other.  Nothing contained herein shall be construed within said thirty (30) days
after the date of Lease termination as aforesaid as a consent by Landlord to the
occupancy or possession of the Leased  Premises by Tenant after the  termination
of the Lease, and Landlord,  upon said termination,  if Landlord elects to treat
Tenant as a  trespasser,  shall be  entitled  to the  benefit of all  general or
public  laws  relating  to the speedy  recovery  of the  possession  of land and
tenements held over by Tenant,  whether now or hereafter in force and effect. If
Tenant fails to  surrender  the Leased  Premises  upon the  expiration  or other
termination  of this Lease  despite  demand to do so by  Landlord,  Tenant shall
indemnify,  defend,  and hold Landlord harmless from all injury,  loss,  claims,
expenses and  liability,  including  without  limitation,  any claim made by any
succeeding  tenant and any  attorneys'  fees,  founded on or resulting from such
failure to surrender.

         15.  Assignment and Subletting.

                         (a)  Assignment  by Tenant.  Tenant  shall not  assign,
mortgage or encumber this Lease, or any right  hereunder,  nor sublet the Leased
Premises  or any part  thereof,  nor permit the  Leased  Premises  to be used by
others without the prior written consent of Landlord,  which consent shall be at
Landlord's  sole  discretion.   If  Tenant  is  a  corporation,   unincorporated
association or partnership,  then the transfer,  assignment or  hypothecation of
any stock or interest in such  corporation,  association or partnership so as to
result in a change of fifty percent  (50%) or more in the  ownership  thereof by
the person, persons or entities owning said entity as of the date of this Lease,
without  the prior  written  consent of  Landlord  (which  consent  shall not be
unreasonably withheld or delayed),  shall be deemed an assignment made in breach
of this covenant. Landlord's consent in any specific instance to any assignment,
mortgage, encumbrance, subletting or use of the Leased Premises and its





                                      -13-




collection and acceptance of rent from any such approved assignee,  subtenant or
other  occupant  shall  neither  constitute a waiver of the  provisions  of this
paragraph,  nor  be  construed  as  permission  of  any  subsequent  assignment,
mortgage, encumbrance, subletting or use without compliance with this paragraph.
Without the prior  written  consent of Landlord,  this Lease and the interest of
Tenant, or any assignee of Tenant, shall not pass by operation of law, nor shall
it be subject to garnishment  or sale under  execution in any suit or proceeding
which may be brought  against  or by  Tenant,  or any  assignee  of  Tenant.  No
assignment of this Lease, sublease of all or any portion of the Leased Premises,
or collection of rent from an assignee or subtenant (whether or not permitted by
Landlord) shall relieve Tenant of its obligations  hereunder.  In the event that
Landlord gives Tenant its written consent to assign,  transfer, or sublet all or
a portion of the Leased  Premises to a third party which is unrelated to Tenant,
any monthly rent or other  payment  accruing to Tenant as the result of any such
assignment,  transfer or sublease, including any lump sum or periodic payment in
any manner relating to such assignment, transfer or sublease, which is in excess
of the Minimum Annual Rent and Additional  Rent then payable by Tenant under the
Lease shall be paid by Tenant to Landlord monthly as Additional Rent,  excluding
any reasonable expenses incurred by Tenant in connection with such assignment or
subletting,  e.g.  legal fees and brokers'  commissions.  Landlord may require a
certificate  from  Tenant  specifying  the full  amount of any such  payment  of
whatsoever  nature.  Any  reasonable  costs and expenses,  including  reasonable
attorneys'  fees  incurred  by  Landlord  in  connection  with any  proposed  or
purported assignment, transfer or sublease shall be borne by Tenant and shall be
payable to Landlord as Additional Rent within five (5) days of demand therefor.

           Notwithstanding  anything  herein to the contrary,  Tenant shall have
the right,  without  Landlord's prior written  consent,  to assign this Lease or
sublet  the  Leased  Premises  to any parent  corporation  of Tenant,  or to any
subsidiary of any parent corporation of Tenant, subject to the following express
conditions:

               (i) No such  assignment  or  sublease  shall be deemed to release
                   Tenant  from   continuing   liability  for  all  of  Tenant's
                   covenants  and  obligations   under  this  Lease,  or  Boston
                   Biomedica,  Inc. ("Tenant's  Guarantor") from its obligations
                   under its Guaranty; and

               (ii)Any assignee or subtenant  must  expressly  assume in writing
                   all of the  covenants  and  obligations  of Tenant under this
                   Lease, joint and severally with Tenant.

              Further,  Landlord agrees not to unreasonably withhold its consent
to an  assignment  of this Lease (or to a sale or transfer  of  Tenant's  stock)
resulting from a merger,  consolidation,  corporate  reorganization  (other than
pursuant to the bankruptcy  laws), sale of the assets or other transfer of stock
of Tenant, subject to the following conditions:

               (i) Such assignee or transferee, as the case may be, shall have a
                   net worth at least  equal to that of  Tenant,  as of the date
                   hereof,  or the  date  of  such  request  for  consent  to an
                   assignment or transfer, whichever is greater;

              (ii) No such  assignment  shall  be  deemed  to  release  Tenant's
                   Guarantor from its obligations under its Guaranty; and

              (iii)Such  assignee  or  transferee,  as the  case  may  be,  must
                   expressly assume in writing all of the





                                      -14-





                   covenants and obligations of Tenant under this Lease, jointly
                   and severally with Tenant.

           Further,  any  issuance  by Tenant of its  capital  stock in a public
offering which is effected in compliance with the  registration  requirements of
the  Securities  Act  of  1933,  as  amended,  and  the  rules  and  regulations
thereunder,  shall not be deemed to be a change in control or an  assignment  of
this Lease requiring Landlord's consent.

                  (b)  Assignment by Landlord.  It is expressly  understood  and
agreed that this Lease and all rights of Landlord  hereunder  shall be fully and
freely  assignable by Landlord without notice to, or consent of, Tenant.  In the
event of the transfer and  assignment by Landlord of its interest in this Lease,
Landlord shall thereby be released from any  responsibility  for the performance
of obligations  thereafter accruing hereunder,  and Tenant agrees to look solely
to  such  successor  in  interest  of  the  Landlord  for  performance  of  such
obligations.  Nothing  contained  herein  shall  prevent  Tenant from looking to
Landlord  for the  performance  of  obligations  of which  Landlord  has  actual
knowledge and which predate the effective date of the transfer and assignment by
Landlord  of its  interest in this Lease.  The term  "Landlord"  as used in this
Lease shall mean the owner of the Leased Premises,  at the time in question.  In
the event of a transfer (whether  voluntary or involuntary) by such owner of its
interest in the Leased  Premises,  such owner shall  thereupon  be released  and
discharged from all covenants and obligations of the Lease thereafter  accruing,
but such covenants and  obligations  shall be binding during the Lease Term upon
each new owner for the duration of such owner's ownership.

            16. Bankruptcy.

                   (a) The following  shall be Events of  Bankruptcy  under this
Lease:  (1) Tenant or any  guarantor  of Tenant's  obligations  under this Lease
("Tenant's  Guarantor") becoming insolvent,  as that term is defined in Title 11
of the United States Code (the "Bankruptcy  Code"), or under the insolvency laws
of any state,  district,  commonwealth  or territory  of the United  States (the
"Insolvency  Laws");  (2) the  appointment of a receiver or custodian for any or
all of Tenant's or Tenant's  Guarantor's  property or assets, or the institution
of a  foreclosure  action upon any of Tenant's or Tenant's  Guarantor's  real or
personal  property;  (3) the filing of a voluntary petition under the provisions
of the Bankruptcy Code or Insolvency Laws by Tenant or Tenant's  Guarantor;  (4)
the filing of an involuntary  petition  against Tenant or Tenant's  Guarantor as
the subject debtor under the Bankruptcy  Code or Insolvency  Laws,  which either
(A) is not dismissed within one hundred twenty (120) days of the date of filing,
or (B) results in the issuance of an order for relief against the debtor; or (5)
Tenant's or Tenant's  Guarantor's  making or consenting to an assignment for the
benefit of creditors or a common law composition of creditors.

                   (b) Upon occurrence of an Event of Bankruptcy, Landlord shall
have all rights and  remedies  available  to  Landlord  pursuant  to Section 18;
provided, however, that while a case in which Tenant is the subject debtor under
the  Bankruptcy  Code is pending,  Landlord  shall not  exercise  its rights and
remedies pursuant to Section 20 so long as (1) the Bankruptcy Code prohibits the
exercise  of  such  rights  and  remedies,  and (2)  Tenant  or its  Trustee  in
Bankruptcy  (hereinafter  referred to as "Trustee") (i) cures all defaults under
this Lease, (ii) compensates  Landlord for monetary damages incurred as a result
of such defaults, (iii) provides adequate assurance of future performance on the
part of Tenant as debtor in  possession  or on the part of the assignee  tenant,
and (iv) complies with all other  requirements  of the Bankruptcy  Code and this
Lease.




                                      -15-


          17. Default. Each of the following shall be deemed a default by Tenant
 and a material breach of this Lease:

                      (a)   An Event of Bankruptcy as defined in Section 16;

                      (b)   An assignment or encumbrance of Tenant's interest
                            in  this  Lease  or  the  Leased  Premises  or  a
                            subletting of any part of the Leased  Premises in
                            violation of Section 15;

                      (c)   A  failure  by  Tenant  to make  any  payment  of
                            Minimum  Annual  Rent or  Additional  Rent within
                            five (5) days of receipt of written  notice  that
                            such  payment  was not  received  on its due date
                            (provided that Landlord shall not be obligated to
                            provide Tenant with such written notice more than
                            twice during any twelve  month period  during the
                            Lease  Term,  and after  receipt  of such  second
                            notice,   Tenant  shall  be  deemed  in  default,
                            without  further  notice,  if any such payment is
                            not received by Landlord on its due date);

                      (d)   Abandonment of the Leased Premises; and

                      (e)   A failure  by Tenant  in the  performance  of any
                            other term,  covenant,  agreement or condition of
                            this Lease on the part of Tenant to be  performed
                            after  fifteen  (15)  days  notice,  or  if  such
                            default  cannot  reasonably  be cured within said
                            fifteen  (15)  day  period  and  Tenant  does not
                            commence  to  diligently  pursue the same  within
                            said  fifteen  (15) day period and to continue to
                            diligently pursue the same until remedied.

Landlord  agrees that it shall not exercise  any rights or  remedies,  which are
available  to it pursuant to the terms of Section 18, as a result of an event of
default described in Section 17 (b) or (d) above,  unless and until Landlord has
provided  Tenant  with a period of fifteen  (15) days  after  receipt of written
notice thereof within which to cure such default.

          18. Landlord's Rights Upon Tenant's Default. Upon default by Tenant of
any of the terms or  covenants  of this  Lease,  Landlord  shall be  entitled to
remedy such default as follows:

                 (a) Landlord  shall have the right,  immediately or at any time
                     after  said  default,  without  further  notice  to  Tenant
                     (unless  otherwise  provided  herein),  to enter the Leased
                     Premises, without terminating this Lease or being guilty of
                     trespass,  and do any and all  acts as  Landlord  may  deem
                     necessary,  proper or convenient to cure such default,  for
                     the account and at the expense of Tenant, and Tenant agrees
                     to pay to Landlord  as  Additional  Rent all damage  and/or
                     expense  incurred  by  Landlord  in  so  doing,   including
                     interest  at the  Penalty  Rate from the due date until the
                     date  payment is received by  Landlord.  The making of such
                     payment or the taking of such action by Landlord  shall not
                     be deemed to cure the default or to stop  Landlord from the
                     pursuit of any remedy to which Landlord would  otherwise be
                     entitled.

                 (b) Landlord shall,  following said default,  have the right to
                     terminate this Lease and/or Tenant's right to possession of
                     the Leased  Premises and,  with or without  legal  process,
                     take  possession of the Leased  Premises and remove Tenant,
                     any  occupant  and any property  therefrom,  without  being
                     guilty of trespass and without  relinquishing any rights of
                     Landlord  against  Tenant.  Landlord  shall be  entitled to
                     recover




                                      -16-




damages from Tenant in an amount  equal to the amount  herein  covenanted  to be
paid as Minimum Annual Rent during the remainder of the Lease Term, said Minimum
Annual Rent for the full term then  remaining  having been fully  accelerated at
the  option  of  Landlord,  together  with (i) all  reasonable  expenses  of any
proceedings (including,  but not limited to, legal expenses and attorney's fees)
which may be necessary in order for Landlord to recover possession of the Leased
Premises,  (ii) the reasonable expenses of the re-renting of the Leased Premises
(including,  but not limited to, any commissions  paid to any real estate agent,
advertising expense and the costs of such alterations, repairs, replacements and
decoration  or  re-decoration  as  Landlord,  in its  sole  judgment  reasonably
exercised,  considers  advisable and necessary for the purpose of re-renting the
Leased  Premises),  and (iii) interest computed at the Penalty Rate from the due
date until paid;  provided,  however,  that said damages  shall be discounted to
present  value using a discount  factor of 5%, and  further  that there shall be
credited  against the amount of such  damages  all amounts  received by Landlord
from such  re-renting of the Leased  Premises and such amounts shall be refunded
to Tenant.  No act or thing done by Landlord shall be deemed to be an acceptance
of a surrender of the Leased  Premises,  unless Landlord shall execute a written
agreement of surrender with Tenant.  Tenant's  liability  hereunder shall not be
terminated by the  execution of a new lease of the Leased  Premises by Landlord.
In the event  Landlord does not exercise its option to accelerate the payment of
Minimum  Annual  Rent as  provided  hereinabove,  then  Tenant  agrees to pay to
Landlord, upon demand, the amount of damages herein provided after the amount of
such damages for any month shall have been ascertained;  provided, however, that
any  expenses  incurred by Landlord  shall be deemed to be a part of the damages
for the month in which they were  incurred.  Separate  actions may be maintained
each month or at other times by Landlord  against  Tenant to recover the damages
then due,  without  waiting until the end of the term of this Lease to determine
the aggregate amount of such damages.

              (c) Upon any  default  by Tenant  to pay  Minimum  Annual  Rent or
Additional  Rent,  Landlord shall have a lien upon the property of Tenant in the
Leased  Premises for the amount of any unpaid  Minimum Annual Rent or Additional
Rent. In such event,  Tenant shall not remove any of Tenant's  property from the
Leased Premises except with the prior written consent of Landlord, which consent
shall be granted at Landlord's sole and absolute discretion.

              (d) All rights and remedies  provided to either Landlord or Tenant
herein as a result of a default by the other party shall be cumulative, and none
shall exclude any other right or remedy  allowed by law. For the purposes of any
suit  brought or based  hereon,  this Lease shall be construed to be a divisible
contract,  to the end that successive actions may be maintained on this Lease as
successive periodic sums mature hereunder.

        19.  Lender Requirements.

              (a)  Subordination.  Tenant  agrees that this Lease is subject and
subordinate  to the lien of any  existing  mortgage  or deed of trust which is a
lien upon the Property or any part thereof on the Rent Commencement Date, and to
all  renewals,  modifications,   consolidations,   replacements  and  extensions
thereof,  and to all  advances  made or  hereafter  to be made upon the security
thereof.  Landlord  agrees that it shall use reasonable  efforts to acquire from
any  such  existing  mortgagee  or  holder  of  an  existing  deed  of  trust  a
non-disturbance agreement in such lender's usual form for the benefit of Tenant.
Tenant  agrees  that this Lease is and shall be subject and  subordinate  to the
lien of any  future  mortgages  or deeds of trust  which at any time  during the
Lease Term may be made a lien upon the Property or any part thereof,  and to all
advances made or hereafter to be





                                      -17-




made  upon the  security  thereof;  provided  that such  subordination  shall be
effective  only upon the  delivery to Tenant of a  non-disturbance  agreement in
such lender's  usual form for the benefit of Tenant by such future  mortgagee or
holder  of  a  deed  of  trust.   These   subordination   provisions   shall  be
self-operative  and no further  instrument of  subordination  shall be required.
Tenant agrees to execute and deliver,  upon request,  such further instrument or
instruments  confirming this subordination as shall be desired by Landlord or by
any mortgagee or proposed mortgagee;  and Tenant hereby constitutes and appoints
Landlord  as  Tenant's  attorney-in-fact  to  execute  any  such  instrument  or
instruments.  Tenant  further  agrees  that,  at the option of the holder of any
mortgage  or of the  trustee  under  any deed of trust,  this  Lease may be made
superior  to said  mortgage  or deed of  trust  by the  insertion  therein  of a
declaration  that  this  Lease  is  superior  thereto,   and  to  all  renewals,
modifications, consolidations, replacements and extensions thereof.

              (b)  Attornment.  In the event any proceedings are brought for the
foreclosure of, or in the event of exercise of the power of sale under, any deed
to secure a debt given by Landlord  and  covering  the Leased  Premises,  Tenant
shall execute such attornment  agreement as shall be reasonably required by said
purchaser,  pursuant to the terms of which Tenant  recognizes  such purchaser as
the owner and landlord under this Lease, and the purchaser  recognizes Tenant as
the tenant under this Lease.

              (c) Notice to Mortgagee  Upon Landlord  Default.  Tenant agrees to
give any mortgagee by certified mail,  return receipt  requested,  a copy of any
notice of default served upon Landlord,  provided that before such notice Tenant
has been notified in writing of the address of such  mortgagee.  Tenant  further
agrees that if Landlord  shall have failed to cure such default  within the time
provided for in this Lease, then mortgagee shall have an additional fifteen (15)
days within which to cure such default; provided,  however, that if such default
cannot be reasonably cured within that time, then such mortgagee shall have such
additional  time as may be  necessary  to cure such default so long as mortgagee
has  commenced and is  diligently  pursuing the remedies  necessary to cure such
default  (including,   without  limitation,   the  commencement  of  foreclosure
proceedings,  if  necessary),  in which event this Lease shall not be terminated
while such remedies are being so diligently pursued. In the event of the sale of
the Property or the Leased Premises, by foreclosure or deed in lieu thereof, the
mortgagee or purchaser at such sale shall be  responsible  for the return of the
security  deposit only to the extent that such  mortgagee or purchaser  actually
received the  security  deposit.  In  addition,  Tenant shall not pay any rental
hereunder for more than one (1) month in advance.

        20. Estoppel  Certificates.  Tenant agrees, at any time and from time to
time,  upon not less than five (5) business  days prior  notice by Landlord,  to
execute,  acknowledge  and  deliver to  Landlord  a  statement  in  writing  (i)
certifying  that this  Lease is  unmodified  and in full force and effect (or if
there have been  modifications  the nature of same),  (ii)  stating the dates to
which the  Minimum  Annual  Rent and  Additional  Rent have been paid by Tenant,
(iii)  stating  whether or not to the best  knowledge of Tenant,  Landlord is in
default in the performance of any covenant,  agreement or condition contained in
this Lease,  and, if so,  specifying  each such default of which Tenant may have
knowledge,  (iv) stating the address to which  notices to Tenant should be sent,
and (v) certifying such other matters as may be requested by Landlord.  Any such
statement  delivered  pursuant  hereto  may be  relied  upon by an  owner of the
Property,   any  prospective  purchaser  of  the  Property,   any  mortgagee  or
prospective mortgagee of the Property, or of Landlord's interest therein, or any
prospective assignee of any such mortgage.




                                      -18-




        21.   Damage by Fire or Other Casualty.

              (a)  Restoration.  If the Leased Premises shall be damaged by fire
or other  casualty  but such damage does not render the Leased  Premises  wholly
unfit for Tenant's  business  operations  as shall be determined by Landlord and
Tenant in their reasonable business judgment,  Landlord,  at Landlord's expense,
shall  promptly  restore  the Leased  Premises,  and Tenant,  at  Tenant's  sole
expense,  shall  promptly  restore all leasehold  improvements  installed in the
Leased  Premises  by  Tenant  or at  Tenant's  request  and its  own  furniture,
furnishings,   trade  fixtures  and  equipment.  No  penalty  shall  accrue  for
reasonable  delay which may arise by reason of  adjustment  of  insurance on the
part of  Landlord,  or on account of labor  problems,  or any other cause beyond
Landlord's  reasonable  control.  Minimum Annual Rent and Additional  Rent shall
abate  proportionately  (based on the  proportion  of the number of square  feet
rendered  untenantable  to the  total  number  of  square  feet  of  the  Leased
Premises),  from  the  date of the  damage  or  destruction  until  the date the
Landlord has substantially completed such restoration.  Notwithstanding anything
stated to the contrary herein,  in the event that such damage shall occur during
the last year of the Lease Term,  Landlord  shall not be required to restore the
Leased Premises.

               (b) Termination. If the Leased Premises are substantially damaged
or are rendered substantially  untenantable by fire or other casualty during the
Lease  Term to such an extent  that it is  rendered  substantially  unusable  by
Tenant for the purposes  originally  contemplated by this Lease,  Landlord shall
restore or repair the same unless  expressly not required to do so under Section
21(c).  If such damage occurs,  however,  at any time during the Lease Term, and
(i) Landlord's  architect  certifies that the Leased Premises cannot be repaired
within one hundred  twenty (120)  working  days of normal  working  hours,  said
period  commencing  on the  casualty  date,  or (ii)  Landlord  shall  decide to
demolish the Leased  Premises or not to rebuild it, then  Landlord  may,  within
ninety  (90) days after  such fire or other  casualty,  terminate  this Lease by
giving Tenant notice of such decision, and thereupon the Lease Term shall expire
by lapse of time upon the third day after such notice is given, and Tenant shall
thereupon vacate the Leased Premises and surrender the same to Landlord.  In the
event that damage to the Leased Premises cannot be repaired  sufficiently within
one hundred  twenty (120) days after such fire or other  casualty so that Tenant
can commence to refixture the Leased  Premises for the use thereof as originally
contemplated  by this Lease,  then Tenant shall have the right to terminate this
Lease by giving  Landlord  written notice thereof within said one hundred twenty
(120) day period,  and  thereupon  the Lease Term shall  expire by lapse of time
upon the third day after such notice is given, and Tenant shall thereupon vacate
the Leased Premises and surrender the same to Landlord.  Upon the termination of
this Lease under the conditions  hereinbefore  provided,  Tenant's liability for
Minimum Annual Rent and Additional  Rent shall cease as of the day following the
casualty.

              (c) Lender's Approval. Notwithstanding anything to the contrary in
this Section or in any other provision of this Lease, any obligation (under this
Lease or  otherwise)  of  Landlord  to restore  all or any portion of the Leased
Premises  shall be subject to Landlord's  receipt of approval of the same by the
mortgagee(s) of Landlord (and any other approvals  required by applicable laws),
as well as  receipt  from any such  mortgagee(s)  of such fire and other  hazard
insurance  policy proceeds as may have been assigned to any such  mortgagee;  it
being  agreed that if Landlord has not received  such  approval(s)  and proceeds
within one hundred and eighty (180) days after any such casualty,  then Landlord
shall have the option to terminate this Lease, at any time thereafter, by notice
to Tenant. Landlord shall diligently




                                      -19-



pursue the receipt of all  approvals  and insurance  policy  proceeds  which are
described in this Section 21(c).

          22.  Condemnation.  In the event the whole or a "substantial part" (as
hereinafter  defined)  of the Leased  Premises  shall be taken for any public or
quasi-public  purpose by any lawful  power or authority by exercise of the right
of  appropriation,  condemnation or eminent domain, or sold to said authority to
prevent such taking (collectively referred to herein as a "taking"),  this Lease
shall  terminate  effective  as  of  the  date  possession  is  required  to  be
surrendered to said  authority,  and the Minimum Annual Rent and Additional Rent
shall  be  apportioned  as  of  the  date.  For  purposes  of  this  Section,  a
"substantial part" of the Leased Premises shall be considered to have been taken
if fifty  percent  (50%) or more of the Leased  Premises is taken or  condemned.
Tenant shall not assert any claim against  Landlord or the taking  authority for
any compensation  arising out of or related to such taking and Landlord shall be
entitled to receive the entire  amount of any award  without  deduction  for any
estate or interest of Tenant; provided,  however, that nothing contained in this
section  shall be deemed to give  Landlord  any  interest  in any award  made to
Tenant for the taking of personal  property and fixtures  belonging to Tenant or
for Tenant's moving  expenses,  as long as such award is made in addition to and
separately  stated from any award made to Landlord  for the Leased  Premises and
the  Property.  If less than fifty  percent  (50%) of the Leased  Premises is so
taken, the Lease shall continue to be in full force and effect,  and the Minimum
Annual Rent and Additional  Rent shall be adjusted  (based on the ratio that the
number of square feet of rentable area taken from the Leased  Premises  bears to
the number of rentable square feet in the Leased Premises  immediately  prior to
such taking) as of the date  possession  is required to be  surrendered  to said
authority;  provided,  however,  Landlord shall have the right to determine that
the  Leased  Premises  should be  demolished  and not  rebuilt,  in which  event
Landlord may, within ninety (90) days after such taking, terminate this Lease by
giving Tenant notice of such decision, and thereupon the Lease Term shall expire
by lapse of time upon the third day after such notice is given, and Tenant shall
thereupon vacate the Leased Premises and surrender the same to Landlord.  In the
event that the Lease  remains in full  force and effect in  accordance  with the
terms  described  above,  Landlord  shall be obligated to repair and restore the
Leased  Premises  to usable  condition  by Tenant,  and such  repair  shall be a
condition precedent to the continued effectiveness of this Lease. Landlord shall
have no obligation to contest any taking.

          23. Landlord's Liability. Landlord, or its agents, shall not be liable
for any injury or damage to persons or property resulting from fire,  explosion,
falling plaster, steam, gas, electricity, water, rain, or leaks from any part of
the Leased Premises, or from the pipes, conduits,  appliances or plumbing works,
or by dampness or by any other cause of whatsoever  nature,  unless caused by or
due to the gross negligence of Landlord, its agents, servants, or employees. All
personal  property and equipment  located in the Leased Premises shall be at the
risk of Tenant.

          24. Tenant's and Landlord's Liability. Tenant shall reimburse Landlord
for all expense, damages or fines, incurred or suffered by Landlord by reason of
any breach,  violation or nonperformance by Tenant, or its agents,  servants, or
employees,  of any  covenant  or  provision  of  this  Lease  or the  Rules  and
Regulations promulgated by Landlord hereunder from time to time, or by reason of
damage to persons or property  caused by moving  property of or for Tenant in or
out of the  Property,  or by the  installation  or removal of furniture or other
property  of or for  Tenant,  by reason of or arising  out of the  carelessness,
negligence or improper conduct of Tenant,  or its agents,  servants,  employees,
invitees or licensees in the use or





                                      -20-




occupancy of the Leased  Premises or the common areas of the Property.  Landlord
shall reimburse Tenant for all expense,  damages or fines,  incurred or suffered
by Tenant by reason of any breach,  violation or nonperformance by Landlord,  or
its agents,  servants, or employees, of any covenant or provision of this Lease,
by reason of or arising out of the gross negligence of Landlord,  or its agents,
servants, employees, invitees or licensees.

          25. Indemnity.

                 (a) By Tenant.  Tenant shall  indemnify and defend Landlord and
its agents and  employees  and save them  harmless  from and against any and all
claims,  actions,  damages,  liabilities  and expense in connection with loss of
life,  personal  injury  and/or  damage to property  arising  from or out of any
occurrence in, upon or at the Leased Premises, or the occupancy or use by Tenant
of the Leased Premises or any part thereof,  or occasioned  wholly or in part by
any act or omission of the Tenant, its agents, contractors, employees, servants,
invitees or licensees,  whether  inside the Leased  Premises or elsewhere in the
Property.

                 (b) By Landlord. Landlord shall indemnify and defend Tenant and
its agents and  employees  and save them  harmless  from and against any and all
claims,  actions,  damages,  liabilities  and expense in connection with loss of
life,  personal injury and/or damage to property occasioned wholly or in part by
any  act or  omission  of the  Landlord,  its  agents,  contractors,  employees,
servants, invitees or licensees, whether inside the Leased Premises or elsewhere
in the Property.

          26. Tenant's Insurance.

                 (a)  Coverages.  Tenant  shall have  issued,  pay the  premiums
therefor,  and  maintain in full force and effect  during the Lease Term and any
option period:

                                 (i)        Comprehensive      Liability.      A
                                            commercial     general     liability
                                            insurance   policy  or  policies  in
                                            which the  Landlord  and  Landlord's
                                            mortgagee(s)  (and  such  additional
                                            persons and/or  entities as Landlord
                                            may request) and Tenant shall be the
                                            insured, protecting the Landlord and
                                            Landlord's  mortgagee(s)  (and  such
                                            additional  persons and/or  entities
                                            as Landlord  may request) and Tenant
                                            in  the  amount  of at  least  Three
                                            Million    and    No/100     Dollars
                                            ($3,000,000.00)   combined,   single
                                            limit  coverage  for bodily  injury,
                                            including death, or property damage,
                                            which amount may be  increased  from
                                            time  to  time  by  Landlord  in its
                                            reasonable determination;

                                 (ii)       All-Risk Casualty. All-risk casualty
                                            insurance, naming Landlord (and such
                                            additional  persons and/or  entities
                                            as Landlord  may request) and Tenant
                                            as insureds (as their  interests may
                                            appear), written at replacement cost
                                            value  and  with   replacement  cost
                                            endorsement,  covering all leasehold
                                            improvements installed in the Leased
                                            Premises  by Tenant  or at  Tenant's
                                            request and all of Tenant's personal
                                            property  in  the  Leased   Premises
                                            (including,    without   limitation,
                                            inventory,   trade  fixtures,  floor
                                            coverings,   furniture   and   other
                                            property  removable  by Tenant under
                                            the provisions of this Lease).





                                      -21-




                                 (iii)      Workers' Compensation. If and to the
                                            extent  required  by  law,  workers'
                                            compensation      and     employer's
                                            liability  or similar  insurance  in
                                            form and amounts required by law.

              (b)  Policy   Requirements.   Tenant's  failure  to  provide  such
insurance  or failure to pay the  premiums  when due,  shall be deemed a default
hereunder.  Any monies expended by Landlord to cure said default shall be deemed
Additional  Rent and shall be due and owing with  Tenant's next payment of Basic
Monthly Rent.  All such policies shall contain only such  reasonable  deductible
amounts as may be approved in advance by Landlord and shall  contain a provision
that  Landlord  shall  receive not less than thirty (30) days advance  notice in
writing from the insurance  company of any intention of the insurance company to
cancel  such  policy or  policies.  Tenant  shall  provide  written  evidence to
Landlord of its  acquisition of such policies prior to the  commencement of this
Lease and prior to any renewal  date of such  policies.  All  policies  shall be
carried with a reputable insurance company qualified to do business in the State
of Maryland and rated not lower than A-XII in the A.M. Best Rating Guide.

              (c) No  Limitation  of  Liability.  Neither  the  issuance  of any
insurance  policy  required  under this Lease nor the minimum  limits  specified
herein  shall be  deemed  to limit or  restrict  in any way  Tenant's  liability
arising under or out of this Lease.

        27. Waiver of  Subrogation.  Landlord and Tenant  mutually  covenant and
agree that each party,  in connection  with  insurance  policies  required to be
furnished  in  accordance  with the terms and  conditions  of this Lease,  or in
connection  with insurance  policies  which they obtain  insuring such insurable
interest as Landlord or Tenant may have in its own properties,  whether personal
or real,  shall  expressly  waive  any right of  subrogation  on the part of the
insurer against the Landlord (and any mortgagee requested by Landlord) or Tenant
as the same may be  applicable,  which  right to the  extent not  prohibited  or
violative of any such policy is hereby expressly waived, and Landlord and Tenant
each mutually waive all right of recovery against each other,  their agents,  or
employees for any loss, damage or injury of any nature whatsoever to property or
person for which either party carries  insurance or is required by this Lease to
carry insurance.

        28. No Liens Permitted; Discharged. Tenant will not permit to be created
or to remain  undischarged  any lien,  encumbrance or charge (arising out of any
work done or  materials or supplies  furnished,  or claimed to have been done or
furnished, by any contractor,  mechanic, laborer or materialman or any mortgage,
conditional sale, security agreement or chattel mortgage, or otherwise by or for
Tenant)  which  might be or  become a lien or  encumbrance  or  charge  upon the
Property or any part thereof or the income therefrom.  If any lien, or notice of
lien on  account of an alleged  debt of Tenant or any  notice of  contract  by a
party engaged by Tenant or Tenant's  contractor  to work on the Leased  Premises
shall be filed against the Property or any part thereof,  Tenant, within fifteen
(15)  days  after  notice  of the  filing  thereof,  will  cause  the same to be
discharged of record by payment,  deposit,  bond,  order of a court of competent
jurisdiction or otherwise.  If Tenant shall fail to cause such lien or notice of
lien to be  discharged  within the period  aforesaid,  then,  in addition to any
other right or remedy,  Landlord may, but shall not be obligated  to,  discharge
the same  either by paying the  amounts  claimed to be due or by  procuring  the
discharge  of such lien by  deposit or by  bonding  proceedings  and in any such
event  Landlord  shall be  entitled,  if  Landlord  so  elects,  to  compel  the
prosecution of an action for the





                                      -22-




foreclosure  of such lien by the lienor and to pay the amount of the judgment in
favor of the lienor with interest,  costs and allowances.  Any amount so paid by
Landlord and all  reasonable  costs and  expenses,  including  attorneys'  fees,
incurred by Landlord in connection  therewith,  shall constitute Additional Rent
payable by Tenant  under this Lease and shall be paid by Tenant to  Landlord  on
demand.  Nothing herein  contained shall obligate Tenant to pay or discharge any
lien created by Landlord.

        29. Signs,  Awnings and Canopies.  Tenant will not place or suffer to be
placed or maintained on the exterior of the Leased Premises any sign,  awning or
canopy, or other written matter of any kind, without first obtaining  Landlord's
written approval which shall not be unreasonably  withheld or delayed,  provided
that any such sign,  awning,  canopy or written matter is in compliance with the
applicable federal,  state and/or county  regulations.  Tenant further agrees to
maintain in good  condition and repair at all times such sign,  awning,  canopy,
decoration,  lettering,  or written matter as may be approved. Any of said items
so  installed  without  such  written  approval  and  consent  may be removed by
Landlord at Tenant's expense.

        30. Environmental  Protection.  Tenant and Tenant's employees and agents
shall not dispose of any oil, petroleum or chemical liquids or solids, liquid or
gaseous  products  or any  hazardous  waste or  hazardous  substance  including,
without limitation, asbestos (hereinafter collectively referred to as "hazardous
waste"),  as those terms are used in the Comprehensive  Environmental  Response,
Compensation, and Liability Act of 1980, or in any other federal, state or local
law  governing  hazardous  substances,  as such laws may be amended from time to
time  (hereinafter  collectively  referred to as the "Act"),  at, upon, under or
within the Leased  Premises or the  Property,  or into the  plumbing or sewer or
water  system  servicing  the Leased  Premises  and/or the  Property,  nor shall
Tenant,  its  agents or  employees  cause or  permit  the  discharge,  spillage,
uncontrolled  loss, seepage or filtration of any hazardous waste at, upon, under
or within the Leased  Premises or the  Property or into the plumbing or sewer or
water  system  servicing  the  same.  Notwithstanding  the  foregoing,  Landlord
acknowledges  that the use which  Tenant  contemplates  for the Leased  Premises
involves the use, storage, and disposal of materials which are defined herein as
hazardous  waste,  and Tenant shall have the right to maintain such materials on
the  Leased  Premises  so long as they  are  used,  stored  and  disposed  of in
accordance  with  the  Act.  Tenant  shall  comply  in  all  respects  with  the
requirements  of the Act and  related  regulations,  and shall  notify  Landlord
immediately in the event of its discovery of any hazardous waste at, upon, under
or within the Leased Premises or the Property which has not been used, stored or
disposed  of in  accordance  with the Act.  Tenant  shall  advise  Landlord,  in
writing,  of the  identities  of  hazardous  wastes being used and stored in the
Leased  Premises  promptly upon written  request from Landlord,  but in no event
less  frequently  than once every  twelve (12) months.  Tenant  shall  indemnify
Landlord against all costs, expenses, liabilities, losses, damages, injunctions,
suits, fines,  penalties,  claims, and demands,  including reasonable attorneys'
fees,  arising out of any  violation of or default by Tenant,  and its employees
and agents,  in the  covenants of this Section.  The  provisions of this Section
shall survive the expiration of the Lease Term.

        31.  Notices.  All  notices to be given  under  this  Lease  shall be in
writing and either (i)  hand-delivered,  (ii) sent by Federal  Express (or other
nationally  recognized,  overnight  mail  courier  service),  (iii) or mailed by
United States Certified or Registered Mail,  return receipt  requested,  postage
prepaid. Notices should be delivered as follows:

                     (a)  To Landlord to the attention of the "General  Manager"
                          at the business and mailing address





                                      -23-



                          stated  on  page 1 of  this  Lease,  with  a  copy  to
                          Shulman,  Rogers,  Gandal,  Pordy & Ecker, P.A., 11921
                          Rockville Pike, Suite 300, Rockville,  Maryland 20852,
                          attn: Karl L. Ecker, Esquire. Pursuant to the terms of
                          Section   19(a)   hereof,   for  so  long  as   Signet
                          Bank/Maryland  holds a first lien security interest in
                          the Property,  a copy of any notice of default  served
                          on Landlord shall be delivered to Signet Bank/Maryland
                          at  7700  Wisconsin  Avenue,   Suite  400,   Bethesda,
                          Maryland  20814,  attn:  Ms. Susan  Benninghoff,  Vice
                          President.

                     (b)  To Tenant to the  attention of Richard T.  Schumacher,
                          President,  at the business and mailing address stated
                          on page 1 of this Lease,  with a copy to Brown Rudnick
                          Freed  &  Gesmer,   One  Financial   Center,   Boston,
                          Massachusetts 02111, attn: Howard L. Levin, Esquire.

Any such notice shall be deemed to be received on the date it is  hand-delivered
or delivered by Federal Express (or other nationally recognized,  overnight mail
courier service), or on the third day after the date on which it is deposited in
the U.S. mails.  Landlord,  Tenant and Signet  Bank/Maryland shall each have the
right to change the person  and/or  address to which  notices shall be delivered
upon notice thereof to the other parties sent pursuant to the provisions of this
paragraph.

        32. Time. Landlord and Tenant acknowledge that time is of the essence in
the performance of any and all obligations, terms, and provisions of this Lease.

        33.  Postponement of Performance.  In the event that either party hereto
shall be delayed or hindered in or  prevented  from the  performance  of any act
required  hereunder by reason of strikes,  labor troubles,  inability to procure
labor  or  materials,   failure  of  power,  restrictive  governmental  laws  or
regulations,  riots,  insurrection,  war, acts of God, fire or other casualty or
other reason of a similar or dissimilar nature beyond the reasonable  control of
the party delayed in performing  work or doing acts required  under the terms of
this Lease,  then performance of such act shall be excused for the period of the
delay and the period for the performance of any such act shall be extended for a
period equivalent to the period of such delay; provided, however that nothing in
this  section  shall  excuse any delay in the payment of Minimum  Annual Rent or
Additional  Rent;  and  provided,  further,  that  delays or failures to perform
resulting  from lack of funds shall not be deemed delays  beyond the  reasonable
control of a party.  Nothing  contained  herein  shall be construed to limit the
provisions  concerning the abatement of Minimum Annual Rent and Additional  Rent
resulting  from  fire and  casualty  damage or from  condemnation  damage to the
Leased Premises as more fully described in Sections 21 and 22 hereof.

         34.  Brokers.  Landlord  and Tenant  represent  and warrant each to the
other that neither has authorized any broker,  agent or finder purporting to act
on  either's  behalf in  respect to this Lease  transaction  except the  Leasing
Broker  specified in Section  l(a)(11),  and each hereby agree to indemnify  and
hold  harmless  one from the other from and against any cost,  expense,  claims,
liability or damage resulting from a breach of the  representation  and warranty
herein contained.

        35. No Waiver.  No waiver by  Landlord or Tenant of any breach of any of
the terms, covenants, agreements, or conditions of this Lease shall be deemed to
constitute a waiver of any succeeding breach thereof,  or a waiver of any breach
of any of the other terms, covenants, agreements, and conditions herein






                                      -24-



contained.  No  provision  of this Lease  shall be deemed to have been waived by
Landlord or Tenant,  unless such waiver be in writing  signed by such party.  No
employee of Landlord or of Landlord's  agents shall have any authority to accept
the keys of the Leased  Premises  prior to  termination  of the  Lease,  and the
delivery of keys to any  employee of Landlord  or  Landlord's  agents  shall not
operate as a termination of the Lease or a surrender of the Leased Premises. The
receipt by  Landlord of any payment of Minimum  Annual Rent or  Additional  Rent
with knowledge of the breach of any covenant of this Lease shall not be deemed a
waiver of such  breach.  The failure of Landlord to enforce any of the Rules and
Regulations made a part of this Lease, or hereafter  adopted,  against Tenant or
any other tenant in the Property  shall not be deemed a waiver of any such Rules
and Regulations.

         36. Amendments.  This Lease and the Exhibits attached hereto,  together
with  the  terms  and  conditions  of that  certain  Assets  for  Cash  Purchase
Agreement,  of even  date,  entered  into by and  between  Landlord,  Tenant and
Tenant's  Guarantor,  which  describe the sale and purchase of certain assets by
Landlord to Tenant and Tenant's Guarantor,  contain the entire agreement between
the parties,  and any agreement  hereafter  made shall be ineffective to change,
modify,  discharge  or effect an  abandonment  in whole or in part  unless  such
agreement is in writing and signed by the party against whom  enforcement of the
change, modification, discharge or abandonment is sought.

        37.  Applicable  Law. The laws of the State of Maryland shall govern the
validity, performance and enforcement of this Lease.

        38. Transfer of the Property. In the event of the sale or other transfer
of Landlord's  right,  title and interest in the Leased Premises or the Property
(except in the case of a sale- leaseback financing transaction in which Landlord
is the  lessee),  Landlord  shall  transfer  and  assign  to such  purchaser  or
transferee all amounts of pre-paid  Minimum Annual Rent and Additional Rent, and
provided  that the  purchaser or  transferee  shall assume all of the  surviving
liabilities   and   obligations  of  Landlord   hereunder   accruing  after  the
consummation of such sale or transfer, Landlord thereupon shall be released from
all liability and obligations  hereunder  derived from this Lease arising out of
any act,  occurrence or omission  relating to the Leased  Premises or this Lease
occurring after the consummation of such sale or transfer.  Tenant shall have no
right to terminate this Lease, to abate Minimum Annual Rent or Additional  Rent,
nor to deduct from, nor set-off, nor counterclaim against Minimum Annual Rent or
Additional Rent because of any sale or transfer (including,  without limitation,
any sale-leaseback) by Landlord or its successors or assigns.

        39.  Extension  Option.  Provided  (i) that this Lease  shall be in full
force and effect;  (ii) that BTRL  Contracts and Services,  Inc. (or a permitted
assignee  of  Tenant  [which  is a  related  party to  Tenant]  pursuant  to the
provisions of Section 15 hereof) shall be the tenant  hereunder;  and (iii) that
Tenant shall not be in default under any of the terms, provisions,  covenants or
condition  of this Lease,  then,  and only in such event,  Tenant shall have the
right,  at Tenant's  sole  option,  to extend the term of this Lease for two (2)
additional  periods  of five (5)  years  each  ("Extension  Terms").  Each  such
extension  option shall be  exercisable  by Tenant giving  written notice of the
exercise of such  extension  option to  Landlord  no sooner  than three  hundred
sixty-five  (365) days and no later than one hundred  eighty (180) days prior to
the expiration date of the then-current term;  provided,  however,  in the event
Tenant fails to exercise any option to extend during the  aforesaid  period such
extension  option shall become null and void and all rights with respect thereto
and with respect to any subsequent  extension  option shall become null and void
and all rights with respect





                                      -25-




thereto and with respect to any subsequent  extension option shall automatically
terminate  and  expire.  Each  Extension  Term  shall be upon  the  same  terms,
covenants  and  conditions  as set forth  herein with respect to the Lease Term,
except that Minimum Annual Rent payable during each Lease Year of each Extension
Term shall be computed in the  following  manner.  On the first day of the first
Lease Year of the first  Extension Term, and on the first day of each Lease Year
thereafter  during  the  remainder  of the first  Extension  Term and during the
Second  Extension  Term,  the  Minimum  Annual  Rent (then in  effect)  shall be
adjusted by [Language  Deleted Due To  Confidential  Treatment  Request.] of any
change  in the Index now known as  "United  States  Bureau of Labor  Statistics,
Consumer  Price  Index  for All  Urban  Consumers,  All  Items  (1982-1984=100)"
("Index"),  provided, however, that the amount of Minimum Annual Rent payable by
Tenant  during any Lease Year of an Extension  Term  pursuant to this  provision
shall  not  be  less  than  [Language  Deleted  Due  To  Confidential  Treatment
Request.]of the Minimum Annual Rent paid during the previous Lease Year. Subject
to the  foregoing,  each such  adjustment  shall be  accomplished  (and shall be
effective  for the entire then-  operative  Lease Year) by adding to the Minimum
Annual  Rent (then in effect)  the amount  created by  multiplying  the  Minimum
Annual Rent then in effect by the amount created by  subtracting  one (1) from a
fraction,  the numerator of which shall be the most recently  published  monthly
Index figure prior to the date of the  adjustment,  and the denominator of which
shall be the  published  monthly Index figure for the same month of the previous
year.  Landlord shall give Tenant written notice of each such adjustment and the
amount of Minimum Annual Rent payable during the forthcoming  Lease Year. Should
said Index cease to be published, then the closest similar published Index by an
agency of the United States Government shall be substituted.  Should there be no
such  substitute,  then the parties  hereto  shall,  under rules of the American
Arbitration  Association,  agree to a substitute formula, or source, designed to
accomplish the same original purpose of this provision. This extension option is
personal  to  Tenant,  and shall not be  available  to any  other  subtenant  or
assignee  of the  Lease  (other  than a  party  which  is  related  to  Tenant),
regardless of whether such  sublease or  assignment  was approved by Landlord in
the manner described herein.

        40.  Right of First  Offer.  In the event  that,  during the Lease Term,
Landlord  determines  to sell the  Property to any party which is  unrelated  to
Landlord,  then, provided that (i) this Lease shall be in full force and effect;
(ii) that BTRL Contracts and Services,  Inc. (or a permitted  assignee of Tenant
[which is a related  party to Tenant]  pursuant to the  provisions of Section 15
hereof) shall be the tenant hereunder;  and (iii) Tenant shall not be in default
under any of the terms, provisions, covenants or conditions of this Lease, then,
and only in such  event,  Tenant  shall  have the first  right to  purchase  the
Property upon the following terms and conditions. Promptly after determining the
terms and  conditions  upon which the  Property  shall be sold to a third party,
Landlord shall give Tenant  written notice of its  opportunity to purchase same,
by  presenting  Tenant  with an  execution  copy of a  Contract  of Sale for the
Property  containing all material terms and conditions as determined by Landlord
to be appropriate for the sale of the Property.  Tenant shall exercise its right
of first  offer  by  executing  the copy of the  Contract  of Sale  tendered  by
Landlord and returning it to Landlord  (together with any required earnest money
deposit)  within  thirty  (30)  calendar  days  of the  date on  which  Landlord
delivered  the  proposed  Contract  of Sale to Tenant.  The failure of Tenant to
execute and deliver the Contract of Sale (and required earnest money deposit) to
Landlord   within  the   aforesaid   thirty  (30)   calendar  day  period  shall
automatically  extinguish  Tenant's  right to exercise such right of first offer
with regard to the Property,  and further shall relieve  Landlord of any and all
liability with respect to same; provided that such right of first offer shall be
reinstated,  without  further  act  required  by any  party,  in the event  that
Landlord  has not  settled  on the sale of the  Property  within  three  hundred
sixty-five (365) days of the expiration date of Tenant's right of first offer as
described





                                      -26-



herein.  Notwithstanding  the foregoing,  Landlord shall not thereafter offer to
sell the  Property  to any third  party for a purchase  price which is less than
that offered to Tenant or upon such other material  terms and  conditions  which
are substantially less advantageous to the purchaser, without first renewing its
offer to Tenant to purchase  same at the lesser  amount of  purchase  price (and
affording  Tenant the right to  exercise  its first right of offer in the manner
described  herein).  Should Tenant fail to exercise  properly its right of first
offer as described above, Landlord shall be free to proceed with the sale of the
Property to any third  party,  free and clear of all rights of Tenant;  provided
that such right of first offer shall be reinstated, without further act required
by any party,  in the event  that  Landlord  has not  settled on the sale of the
Property  within three hundred  sixty-five  (365) days of the expiration date of
Tenant's  right of first  offer as  described  herein.  In the event that Tenant
exercises its right of first offer as provided herein,  then Landlord and Tenant
shall  proceed  to  settlement  thereunder  in  accordance  with the  terms  and
conditions of the Contract of Sale. In the event that Tenant thereafter fails to
settle  on its  purchase  of the  Property  in  accordance  with the  terms  and
conditions of the Contract of Sale,  then Landlord shall have the right (but not
the obligation), as determined in its sole and absolute discretion, to terminate
this  Lease,  in  addition  to  exercising  any and all rights  available  to it
pursuant to the terms and  conditions  of the Contract of Sale.  Landlord  shall
exercise its right to terminate  this Lease by giving  written notice thereof to
Tenant,  in which  event this Lease shall  terminate  on the third day after the
giving of such  notice,  and  Tenant  shall  deliver  possession  of the  Leased
Premises to Landlord. This right of first offer is personal to Tenant, and shall
not be available  to any other  subtenant or assignee of the Lease (other than a
party  which is related to  Tenant),  regardless  of whether  such  sublease  or
assignment was approved by Landlord in the manner described herein.

            41.  Right of First  Refusal.  Provided  (i) that  Landlord  has not
offered  Tenant the right to purchase the Property for a purchase price which is
equal to or less than the offer  described below and is upon such material terms
and conditions  which are  substantially  the same or more  advantageous  to the
purchaser  than are contained in the offer  described  below,  and that Tenant's
right of first offer has not expired (and  Tenant's  right under  Section 40 has
not been  reinstated),  all pursuant to the terms and  conditions  of Section 40
hereof; (ii) that this Lease shall be in full force and effect;  (iii) that BTRL
Contracts  and  Services,  Inc. (or a permitted  assignee of Tenant  [which is a
related party to Tenant]  pursuant to the provisions of Section 15 hereof) shall
be the tenant hereunder;  and (iv) that Tenant shall not be in default under any
of the terms,  provisions,  covenants or condition of this Lease, then, and only
in such event,  Tenant  shall have the right of first  refusal to  purchase  the
Property (the "Right of First Refusal") upon the following terms: If at any time
during the Lease  Term,  Landlord  shall  receive a bona fide offer from a third
party for the purchase of the Property,  which offer Landlord desires to accept,
Landlord  promptly  shall  deliver to Tenant a copy of such  offer.  Tenant may,
within  thirty  (30) days after  receipt of such offer,  elect to  purchase  the
Property  on the same  terms  and  conditions  as set  forth in such  offer,  by
delivering  to Landlord  written  notice of said  exercise  within the aforesaid
thirty (30) day period.  In the event that  Landlord  shall receive an offer for
the purchase of the Property  which is not  consummated  by delivering a deed to
the offeror,  Tenant's  Right of First  Refusal as set forth herein shall remain
applicable  to  subsequent  offers made to Landlord.  In the event that Landlord
shall  sell the  Property  after  Tenant  fails to  exercise  its Right of First
Refusal,  such  sale  shall be  subject  to the terms of this  Lease,  provided,
however, the Right of First Offer and the Right of First Refusal as set forth in
this Lease shall  expire  upon the date of  conveyance  of the  Property to said
third party,  and said rights  shall not continue in force or effect,  nor shall
they be applicable to any





                                      -27-



subsequent sale or ownership of the Property by successive parties. In the event
that any  mortgagee or holder of a deed of trust or other  security  interest in
the  Property  shall  foreclose  on the  Property  or  accept  a deed in lieu of
foreclosure  as a result of the failure of  Landlord to pay any debt  secured by
the  Property,  the Right of First  Offer and the Right of First  Refusal as set
forth in this Lease shall expire  automatically  upon the date of  conveyance of
the Property to said mortgagee or holder of a security  interest  therein (or to
any third party  assignee  of said  mortgagee  or holder of a security  interest
therein), and said Right of First Offer and the Right of First Refusal shall not
continue in force or effect, nor shall they be applicable to any subsequent sale
or ownership of the Property by successive parties.

         42. Waiver of Counterclaim and Trial by Jury/Attorneys  Fees.  Landlord
and Tenant  waive  their  right to trial by jury in any  action,  proceeding  or
counterclaim  brought by either of the parties  hereto against the other (except
for personal injury or property damage) on any matters whatsoever arising out of
or in any way  connected  with this Lease,  the  relationship  of  Landlord  and
Tenant,  Tenant's use of or occupancy of the Leased Premises,  and any emergency
statutory  or any  other  statutory  remedy.  Tenant  shall  not  interpose  any
counterclaim(s)  or claim(s)  for  set-off,  recoupment  or deduction of Minimum
Annual Rent or Additional Rent in a summary proceeding for nonpayment of Minimum
Annual Rent or Additional Rent,  unless such counterclaim is mandatory in nature
and must be  interposed  in such  summary  proceeding  initiated  by Landlord or
otherwise be deemed waived.  In the event either Landlord or Tenant institute an
action or  proceeding  against the other to enforce the terms and  conditions of
this Lease,  the  prevailing  party shall be entitled to recover all  reasonable
attorneys fees and costs incurred as a result thereof.

        43.  Separability.  If any  term  or  provision  of  this  Lease  or the
application  thereof to any person or  circumstances  shall,  to any extent,  be
invalid or unenforceable, the remainder of this Lease or the application of such
term or provision to persons or circumstances other than those as to which it is
held invalid or unenforceable, shall not be affected thereby and each other term
and provision of this Lease shall be valid and enforceable to the fullest extent
permitted by law.

        44. Corporate Authority.  Concurrently with the execution of this Lease,
Tenant has  delivered to Landlord a certified  copy of a resolution  of Tenant's
Board of  Directors  (or other  evidence  reasonably  satisfactory  to Landlord)
approving the leasing of the Leased Premises by Tenant pursuant to the terms and
conditions  contained  herein,  stating  that this Lease is fully  binding  upon
Tenant,  and authorizing the execution of this Lease by each person signing this
Lease on behalf of Tenant.

        45. Interpretation.

              (a)  Captions.   The  captions,   marginal   references,   General
Information  sheet,  and table of contents  appearing in this Lease are inserted
only as a matter of convenience and in no way amplify,  define, limit, construe,
or described the scope or intent of this Lease nor in any way affect this Lease.

              (b) Gender.  The neuter,  feminine or masculine  pronoun when used
herein shall each include each of the other  genders and the use of the singular
shall include the plural.

              (c) Covenants. The parties hereto agree that all the provisions of
this Lease are to be construed as covenants  and  agreements as though the words
importing  such covenants and  agreements  were used in each separate  provision
hereof.

              (d)  Interpretation. Although the printed provisions of this Lease
were drawn by Landlord, this Lease shall





                                      -28-




not be  construed  for or against  Landlord  or Tenant,  but this Lease shall be
interpreted in accordance with the general tenor of the language in an effort to
reach the intended result.

         46. Landlord's Agreement re: Contract of Sale of the Property. Landlord
agrees  that,  during the Lease Term and prior to its  execution of any contract
for the sale of the Property to a prospective  purchaser,  it shall give written
notice of the  existence of this Lease and Tenant's  occupancy  rights in and to
the  Leased  Premises  (together  with a  copy  of  this  Lease),  to  any  such
prospective purchaser of the Property.

         47. Reasonableness of Expenses. Wherever it is required by the terms of
this  Lease  that one party  reimburse  the other  party for costs and  expenses
incurred in connection  with the performance of an obligation or the exercise of
a right described  herein,  unless  expressly  stated  otherwise,  all costs and
expenses for which such  reimbursement  is sought shall be  reasonable in amount
and nature,  as  determined  in  accordance  with local  standards of commercial
reasonableness in the District of Columbia metropolitan area.

         48. Limits of Landlord's Liability.  In the event that any mortgagee or
holder  of a deed of trust or other  security  interest  in the  Property  shall
foreclose on the Property or accept a deed in lieu of foreclosure as a result of
the  failure  of  Landlord  to pay  any  debt  secured  by the  Property,  then,
thereafter,  neither the owner of the  Property,  as  Landlord,  nor its agents,
employees or officers, whether disclosed or undisclosed, shall have any personal
liability under any provision of this Lease,  and if such a subsequent  owner of
the Property, as Landlord, defaults in the performance of any of its obligations
hereunder or otherwise,  Tenant shall look solely to Landlord's equity, interest
and rights in the  Property  for  satisfaction  of Tenant's  remedies on account
thereof.

        49. Binding Effect. This Agreement shall be binding upon and shall inure
to the benefit of the parties hereto, and the heirs,  personal  representatives,
successors and assigns of said parties.

        IN WITNESS WHEREOF,  the parties hereto have duly executed,  sealed, and
delivered this Lease,  or have caused same to be executed,  sealed and delivered
by their duly authorized attorney-in-fact, as of the day and year above written.

WITNESS                               LANDLORD:
                                      Cambridge Biotech Corporation,
                                         a Delaware corporation


                                      By: /s/ signature unreadable (SEAL)
- ---------------------------             ---------------------------------
                                         /s/ signature unreadable
                                        ---------------------------------


                                      Date of Execution: July 14, 1992
                                                        ---------


WITNESS/ATTEST:                       TENANT:
                                      BTRL Contracts and Services, Inc.,
                                         a Massachusetts corporation



/s/ signature unreadable              By: /s/ signature unreadable (SEAL)
                                        ---------------------------------
                                          /s/ signature unreadable , President
                                        --------------------------

                                      Date of Execution: July 14, 1992
                                                        --------








                                    EXHIBIT C

                              RULES AND REGULATIONS

Tenant agrees as follows:


         1. Tenant will keep the Leased  Premises and  approaches  thereto clean
and free from  rubbish;  will  remove  snow,  ice and debris  from the  adjacent
sidewalks;  will keep all  windows  and any sign neat,  clean and in good order;
will not erect any screen or fence;  and will not  perform  any acts or carry on
any  practices  which may damage the Leased  Premises  or the  Property  or be a
nuisance or menace to other tenants.

        2. Tenant shall not  obstruct or interfere  with the rights of others to
use any Property driveways, parking facilities,  sidewalks, exits, entrances, if
any.

        3. Tenant  shall not store any  material,  supplies,  equipment,  wooden
pallets,  vehicles or anything whatsoever outside of the Leased Premises. If any
such items are not removed within forty-eight (48) hours Landlord shall have the
right  to  remove  the  same,   with  prior  notice  to  Tenant,   and  with  no
responsibility  to  Tenant  for loss or damage  to such  items,  and the cost to
Landlord of such removal shall be deemed to be  Additional  Rent under the Lease
and will be immediately paid by Tenant to Landlord upon demand.

        4. Business and mechanical equipment which cause noise or vibration that
may be  transmitted  to the  structure  of the Leased  Premises  or to any space
therein to such a degree as to be  objectionable to Landlord or any other tenant
of the Property,  shall be placed and maintained by Tenant, at Tenant's expense,
on vibration  eliminators  or other  devices  sufficient  to eliminate  noise or
vibration.

        5. Tenant shall comply with any governmental  energy-saving  rules, laws
or regulations of which Tenant has notice.

        6. The sewage  system shall not be used for any purpose  other than that
for which it was  constructed  and no foreign  substance of any kind  whatsoever
shall be  thrown  therein.  The  expense  of any  breakage,  stoppage  or damage
resulting  from the  violation of this rule shall be borne by the Tenant who, or
whose employees or invitees, shall have caused it.

        7. Should the Tenant,  its agents or invitees,  activate  its  sprinkler
system (if there is one in the Leased Premises), Tenant agrees that it will pay,
as  Additional  Rent to  Landlord,  any  damage to the  Leased  Premises  and to
property of other Property tenants.

        8. All trash and garbage shall be kept within the Leased Premises (or in
a dumpster  placed on the common areas of the Property at a location  reasonably
satisfactory  to Landlord)  and collected on a regular  basis.  Tenant shall not
place in any trash box or receptacle any material which cannot be disposed of in
the ordinary and customary manner of trash and garbage disposal.

        9. Tenant shall comply with all safety,  fire  protection and evacuation
procedures  and  regulations  established by or any  governmental  agency having
jurisdiction.

        10. Tenant assumes any and all  responsibility for protecting the Leased
Premises from theft,  robbery and pilferage which includes  keeping doors locked
and other means of entry to the Leased Premises closed.

        11.  Tenant  shall keep the  inside and the  outside of all glass in the
doors and windows within the Leased Premises clean,  keep all exterior  surfaces
of the Leased Premises clean, replace







promptly any cracked or broken glass of the Leased  Premises  with glass of like
kind, color, and quality.

        12. Tenant shall be responsible  for the observance of all the foregoing
rules by Tenant's employees, agents, clients, customers, invitees and guests.

        13.  Tenant  shall  give  Landlord  immediate  notice in case of fire or
accidents  in the  Leased  Premises,  and in case of  fire or  accidents  on the
Property involving Tenant, its agents, employees or invitees.







                                    GUARANTY


         In consideration of, and as a material  inducement to Cambridge Biotech
Corporation,  a Delaware  corporation  qualified  to do business in the State of
Maryland,  with a  business  and  mailing  address  at  1500  East  Gude  Drive,
Rockville,  MD 20850 (the "Landlord"),  executing and delivering  simultaneously
herewith,  in reliance upon this  Guaranty,  that certain  Lease (the  "Lease"),
dated as of June 30, 1992,  between  Landlord and BTRL  Contracts  and Services,
Inc.,  a  Massachusetts  corporation  qualified  to do  business in the State of
Maryland ("Tenant"),  the undersigned,  Boston Biomedica,  Inc., a Massachusetts
corporation (the  "Guarantor"),  with a business and mailing address at 375 West
Street,  West  Bridgewater,  Massachusetts  02379,  hereby  unconditionally  and
absolutely  guarantees  unto Landlord,  its  successors  and assigns,  the full,
prompt and complete  payment by Tenant of the Minimum Annual Rent and Additional
Rent provided in the Lease,  and the prompt,  faithful and complete  performance
and  observance by Tenant of all of the terms,  covenants and  conditions of the
Lease on the Tenant's part to be performed and/or observed.  Upon the failure of
Tenant to make any such  payment  of  Minimum  Annual  Rent or  Additional  Rent
provided  in the Lease,  or to perform or  observe  any such term,  covenant  or
condition of the Lease on the Tenant's  part to be  performed  and/or  observed,
Guarantor  shall,  promptly upon demand,  pay such required sum to Landlord,  or
perform or observe the required term, covenant or condition of the Lease.

        Guarantor  does hereby  waive notice of any and all defaults on the part
of the Tenant, waives acceptance and notice of acceptance of this Guaranty,  and
waives all demand for payment and/or  performance;  and Guarantor agrees that no
delay on the part of  Landlord  in  enforcing  any of its rights or  remedies or
insisting thereupon,  nor any extension of time nor any changes or modifications
in or to, or in  connection  with the Lease,  shall in any way limit,  affect or
impair the  liability of Guarantor  hereunder;  and Guarantor  hereby  expressly
consents to and  approves  thereof  with the same force and effect as though its
written consent had been given to each of such delays,  extensions,  changes and
modifications.

        This Guaranty is independent of and in addition to any security or other
remedies  which  Landlord  has or may  have  for the  performance  of any of the
obligations on the part of Tenant;  and Guarantor agrees that Landlord shall not
be required to resort to any other security or other remedies before  proceeding
upon this Guaranty, but that Landlord may proceed hereunder against Guarantor at
any time it sees fit,  independently of or concurrently  with any other remedies
it may have.

        This Guaranty shall remain in full force and effect  notwithstanding the
institution by or against Tenant, of bankruptcy,  reorganization,  readjustment,
receivership or insolvency  proceedings of any nature,  or the  disaffirmance of
the Lease in any such proceedings or otherwise.

        If  Guarantor  is a  corporation  and is  merged  into or with any other
company, firm or corporation,  the resulting merged company, firm or corporation
shall become  liable as Guarantor  under this Guaranty to the same extent as the
original named Guarantor hereunder.

        Concurrently  with  the  execution  of  this  Guaranty,   Guarantor  has
delivered to Landlord a certified copy of a resolution of its Board of Directors
(or other evidence  reasonably  satisfactory to Landlord) approving the guaranty
by Guarantor  of Tenant's  obligations  contained  in the Lease  pursuant to the
terms and  conditions  contained  herein,  stating  that this  Guaranty is fully
binding upon  Guarantor,  and authorizing the execution of this Guaranty by each
person signing this Lease on behalf of Guarantor.








         This Guaranty shall be binding upon the undersigned,  the undersigned's
successors  and  assigns,  and  shall  inure to the  benefit  of  Landlord,  its
successors and assigns,  and to the benefit of any successors to the interest of
Landlord under the Lease and/or to the Leased Premises.

         IN WITNESS  WHEREOF,  the  undersigned  has duly executed this Guaranty
under seal as of the 30th day of June, 1992.

WITNESS/ATTEST:                              GUARANTOR:
                                             Boston Biomedica, Inc.


/s/ signature unreadable                     By: /s/ signature unreadable (SEAL)
- ----------------------------                    --------------------------------
Secretary                                       Name: /s/ signature unreadable
                                                     ---------------------------
                                                Title: President
                                                      --------------------------


State of  UNREADABLE
          ------------------
County of UNREADABLE
          ------------------

On this the 14th day of July, 1992,  before me, the subscriber,  a Notary Public
in and  for the  jurisdiction  aforesaid,  personally  appeared  UNREADABLE  who
acknowledged  himself/herself  to be the President of Boston Biomedica,  Inc., a
Massachusetts corporation,  and that he/she, as such President, being authorized
so to do, executed the foregoing and annexed Guaranty for the purposes contained
therein, by signing the name of the corporation by himself/herself as President.

IN WITNESS WHEREOF, I hereunto set my hand and official seal.


                                                   /s/ signature unreadable
                                                   -----------------------------
                                                   Notary Public

                                                   My Commission Expires 11/6/92
                                                                         -------








BTRL Contracts and Services, Inc.
375 West Street
West Bridgewater, Massachusetts 02379


        Re:   Lease  Agreement  Dated  as of June  30,  1992  between  Cambridge
              Biotech  Corporation  and  BTRL  Contracts  and  Services,   Inc.,
              covering  certain  premises  known  as 3  Taft  Court,  Rockville,
              Maryland 20850

Gentlemen:

       Reference is made to the  above-reference  Lease Agreement (the "Lease"),
pursuant to which Cambridge Biotech Corporation  ("Landlord") has leased certain
premises known as 3 Taft Court,  Rockville,  Maryland,  to be BTRL Contracts and
Services, Inc. ("Tenant").

       In  mutual  consideration  of  Landlord  and  Tenant  entering  into  the
above-referenced  Lease,  this will confirm that Landlord and Tenant have agreed
to supplement the provisions of the Lease as follows:

       1.        Landlord  and Tenant have agreed to clarify the  provisions  of
                 Section 4(b)(iii),  relating to insurance,  so as to clarify in
                 the third  paragraph  thereof  that in the event that  Landlord
                 causes its  insurance  carrier  to provide a written  statement
                 reflecting   the   allocation  of  premiums  paid  by  Landlord
                 attributable  to the Leased  Premises (as defined  therein) and
                 the premiums  attributable  to the  insurance  carried on other
                 properties owned by Landlord,  the premiums attributable to the
                 Leased  Premises  shall  be  Tenant's  Proportionate  Share  of
                 insurance costs payable under the Lease.

       2.        Landlord has agreed to provide to Tenant, on a quarterly basis,
                 true and  complete  copies of bank  statements  reflecting  the
                 status of  accounts  in which  monies  have been  deposited  in
                 escrow on  account of real  estate  taxes  pursuant  to Section
                 4(b)(ii) of the Lease,  insurance  premiums pursuant to Section
                 4(b)(iii) of the Lease,  and the Security  Deposit  pursuant to
                 Section 5 of the Lease.

       3.        In the event that  Landlord  refinances  the real  property  of
                 which the Leased Premises constitute a part, Landlord agrees to
                 modify and amend the Lease so as to eliminate  the  limitations
                 on  the  Landlord's  (and  any  subsequent  owner's)  liability
                 pursuant  to  Section  48  of  the  Lease,   unless  Landlord's
                 prospective new mortgage  lender,  if any, refuses (in its sole
                 discretion)  to finance the  property if such  modification  or
                 amendment is made.

      EXECUTED as a sealed instrument as of the 30th day of June, 1992.

TENANT:                                           LANDLORD:

BTRL CONTRACTS  SERVICES, INC.                    CAMBRIDGE BIOTECH CORPORATION


BY: /s/ signature unreadable                      BY: /s/ signature unreadable
  ----------------------------                      ----------------------------
                                                      Vice President