Exhibit 10.30


         REGISTRATION  RIGHTS  AGREEMENT,  dated as of  October  4,  1995  (this
"Agreement"), among DIANON Systems, Inc. a Delaware Corporation (the "Company'),
and the Gilbert Family Trust,  the G.S.  Beckwith  Gilbert  I.R.A.  Contributory
Account and G.S.  Beckwith  Gilbert  (collectively,  the "Investors" and each an
"Investor").  Certain  terms used herein are defined in Section 3 and terms used
but not  defined  herein  shall  have the  meaning  set  forth  in the  Purchase
Agreement (as defined below).

         1.  Background.  Pursuant  to a Stock and Warrant  Purchase  Agreement,
dated as of the date hereof (the  "Purchase  Agreement"),  among the Company and
the Investors, the Investors have purchased from the Company 1,000,000 shares of
the Company's Common Stock, par value $0.01 per share (the "Common Stock"),  and
two-year  warrants (the  "Warrant") to purchase  800,000  shares of Common Stock
(the "Warrant Shares").

         2. Registration Under Securities Act, etc.

         2.1  Registration  on  Request.  (a)  Request.  Subject to Section  2.9
hereof,  upon  the  written  request  of one or more  holders  (the  "Initiating
Holders')  of  Registrable  Securities  representing  not  less  than 30% of the
Registrable  Securities  that the  Company  effect  the  registration  under the
Securities Act of all of such Initiating Holders'  Registrable  Securities,  the
Company will promptly give written notice of such requested  registration to all
registered holders of Registrable Securities, and thereupon the Company will use
its best efforts to effect the registration  under the Securities Act, including
by means of a shelf  registration  pursuant to Rule 415 under the Securities Act
if so requested in such request and if the Company is then  eligible to use such
a registration, of

                  (i) the Registrable  Securities  which the Company has been so
         requested to register by such Initiating Holders, and

                  (ii) all other  Registrable  Securities  which the Company has
         been  requested to register by the holders  thereof by written  request
         given to the  Company  within 30 days after the giving of such  written
         notice  by the  Company  (such  holders  together  with the  Initiating
         Holders are hereinafter  referred to as the "Selling Holders"),  all to
         the extent  requisite  to permit  the  disposition  of the  Registrable
         Securities so to be registered.

         (b) Registration of Other Securities. Whenever the Company shall effect
a registration  pursuant to this Section 2.1 in connection  with an underwritten
offering by one or more Selling Holders of Registrable Securities, no securities
other than Registrable Securities shall be included among the securities covered
by such registration unless (i) the managing  underwriter of such offering shall
have advised each Selling Holder of Registrable Securities to be covered by such
registration  in writing that the inclusion of such other  securities  would not
adversely  affect such  offering  or (ii) the  Selling  Holders of not less than
66-2/3% of all Registrable  Securities to be covered by such registration  shall
have consented in writing to the inclusion of such other securities.

         (c) Registration  Statement Form.  Registrations under this Section 2.1
shall be on such  appropriate form of the Commission as shall be selected by the
Company and as shall be  reasonably  acceptable  to the Selling  Holders of more
than 50% of the Registrable  Securities so to be registered.  The Company agrees
to include in any such  registration  statement all  information  which,  in the
opinion of counsel to the Selling  Holders of  Registrable  Securities  so to be
registered and counsel to the Company, is required to be included.

         (d)  Expenses.  The  Company  will  pay the  Registration  Expenses  in
connection with any registration  requested pursuant to this Section 2.1. If the
Company,  at the request of holders of 66-2/3% of the Registrable  Securities to
be covered by such  registration,  withdraws the  registration  statement before
such registration statement becomes effective, the Selling Holders shall pay all
of the  Registration  Expenses  incurred in  connection  with such  registration
statement.




         (e) Effective Registration Statement. A registration requested pursuant
to this  Section  2.1 shall not be deemed  to have been  effected  (i)  unless a
registration statement with respect thereto has become effective,  (ii) if after
it has become effective, such registration is interfered with by any stop order,
injunction or other order or requirement of the Commission or other governmental
agency or court for any reason not  attributable  to the Selling Holders and has
not thereafter become effective, or (iii) if the conditions to closing specified
in the purchase  agreement or underwriting  agreement,  if any,  entered into in
connection  with such  registration  are not satisfied or waived,  other than by
reason of a failure on the part of the Selling Holders.

         (f) Selection of Underwriters.  The underwriter or underwriters of each
underwritten offering of the Registrable Securities so to be registered shall be
selected by the Selling Holders of more than 50% of the  Registrable  Securities
so to be registered and shall be reasonably acceptable to the Company.

         (g) Priority in Requested Registration.  If the managing underwriter of
any  underwritten  offering  shall advise the Company in writing (with a copy to
each Selling Holder of Registrable Securities requesting  registration) that, in
its  opinion,  the  number  of  securities  requested  to be  included  in  such
registration by the holders of Registrable  Securities  exceeds the number which
can be sold in such  offering  within a price  range  acceptable  to the Selling
Holders of 66-2/3% of the  Registrable  Securities  requested  to be included in
such registration,  the Company will include in such registration, to the extent
of the number  which the  Company is so  advised  can be sold in such  offering,
Registrable  Securities requested to be included in such registration,  pro rata
among the  Selling  Holders on the basis of the  percentage  of the  Registrable
Securities of such Selling Holders requested so to be registered.  In connection
with any such  registration  to which  this  Section  2.1(g) is  applicable,  no
securities  other  than   Registrable   Securities  shall  be  covered  by  such
registration.

         (h) Limitations on Registration on Request. Notwithstanding anything in
this  Section 2.1 to the  contrary,  in no event will the Company be required to
effect, in the aggregate, without regard to the holder of Registrable Securities
making such request, more than two registrations pursuant to this Section 2.1.

         (i)  Withdrawal  of Request.  If holders of 66-2/3% of the  Registrable
Securities  to be covered by  registration  pursuant to this Section 2.1 request
the withdrawal of such registration after the filing thereof with the Commission
but prior to such  registration  becoming  effective the Company shall  withdraw
such registration.

         2.2.  Incidental   Registration.   (a)  Right  to  Include  Registrable
Securities.  If the  Company  at any time  after  the date  hereof  proposes  to
register any of its securities under the Securities Act by registration on Forms
S-1, S-2 or S-3 or any successor or similar  form(s)  (except  registrations  on
such  Forms  or  similar  form(s)  solely  for  registration  of  securities  in
connection  with a stock  option  or  other  employee  benefit  plans,  dividend
reinvestment plans, mergers,  acquisitions,  consolidations,  exchange offers or
subscription  offers),  whether or not for sale for its own account,  subject to
Section 2.9 hereof,  it will each such time give  prompt  written  notice to all
registered  holders of  Registrable  Securities of its intention to do so and of
such  holders'  rights under this Section 2.2.  Upon the written  request of any
such holder (a "Requesting  Holder") made as promptly as practicable  and in any
event  within 15 days after the  receipt of such  notice (7 days if the  Company
states in such  written  notice  or gives  telephonic  notice to all  registered
holders of Registrable Securities,  with written confirmation to follow promptly
thereafter, stating that (i) such registration will be on Form S-3 and (ii) such
shorter  period of time is required  because of a planned  filing  date)  (which
request shall specify the Registrable  Securities  intended to be disposed of by
such Requesting  Holder),  the Company will,  subject to Section 2.9 hereof, use
its best  efforts to effect the  registration  under the  Securities  Act of all
Registrable  Securities  which the Company has been so  requested to register by
the  Requesting  Holders  thereof;  provided,  that if, at any time after giving
written  notice of its  intention  to register any  securities  and prior to the
effective  date of the  registration  statement  filed in  connection  with such
registration,  the Company shall  determine for any reason not to register or to



delay  registration of such securities,  the Company may, at its election,  give
written notice of such  determination  to each Requesting  Holder of Registrable
Securities  and the  Company  shall  (A) in the case of a  determination  not to
register,  be relieved of its obligation to register any Registrable  Securities
in connection with such registration (but not from any obligation of the Company
to pay the Registration  Expenses in connection  therewith),  without prejudice,
however,  to the  rights of any  holder or  holders  of  Registrable  Securities
entitled  to  do  so  to  request  that  such  registration  be  effected  as  a
registration  under Section 2.1, and (B) in the case of a determination to delay
registering,  be permitted to delay  registering any Registrable  Securities for
the  same  period  as  the  delay  in  registering  such  other  securities.  No
registration  effected  under this Section 2.2 shall  relieve the Company of its
obligation  to effect any  registration  upon  request  under  Section  2.1. The
Company will pay all  Registration  Expenses in connection with  registration of
Registrable Securities requested pursuant to this Section 2.2.

         (b) Priority in Incidental  Registrations.  If the managing underwriter
of any  underwritten  offering  shall inform the Company by letter of its belief
that the number or type of  Registrable  Securities  requested to be included in
such  registration  would materially  adversely  affect such offering,  then the
Company will include in such registration,  to the extent of the number and type
which the  Company  is so  advised  can be sold in (or  during the time of) such
offering,  first, all securities  proposed by the Company to be sold for its own
account,  second, such Registrable  Securities  requested to be included in such
registration  pro rata on the basis of the percentage of Registrable  Securities
of such Requesting  Holders requested so to be registered,  and third, any other
securities of the Company requested to be included in such registration pro rata
among the holders thereof based on the percentage of such securities held by the
holders thereof and requested so to be registered.

         2.3. Registration  Procedures.  If and whenever the Company is required
to use its best efforts to effect the registration of any Registrable Securities
under the  Securities Act as provided in Section 2.1 or 2.2, the Company will as
expeditiously as possible:

                  (a)  prepare  and  file  with  the  Commission  the  requisite
         registration  statement to effect such  registration and thereafter use
         its best  efforts to cause such  registration  statement to effect such
         registration  and  thereafter  use  its  best  efforts  to  cause  such
         registration statement to become effective; provided, however, that the
         Company may  discontinue any  registration of its securities  under the
         circumstances  specified  in  Section  2.2(a) at any time  prior to the
         effective date of the registration statement relating thereto;

                  (b) prepare and file with the Commission  such  amendments and
         supplements to such  registration  statement and the prospectus used in
         connection  therewith  as may be  necessary  to keep such  registration
         statement effective and to comply with the provisions of the Securities
         Act with  respect  to the  disposition  of all  Registrable  Securities
         covered  by such  registration  statement  for such  period as shall be
         required for the  disposition  of all of such  Registrable  Securities;
         provided,  that, except with respect to any such registration statement
         filed pursuant to Rule 415 under the  Securities  Act, such period need
         not exceed 120 days;

                  (c) furnish to each seller of Registrable  Securities  covered
         by such registration statement, such number of conformed copies of such
         registration  statement  and of  each  such  amendment  and  supplement
         thereto (in each case including all exhibits), such number of copies of
         the prospectus contained in such registration statement (including each
         preliminary  prospectus  and any  summary  prospectus)  and  any  other
         prospectus filed under Rule 424 under the Securities Act, in conformity
         with the  requirements of the Securities Act, and such other documents,
         as such seller may reasonably request;




                  (d) use its  best  efforts  (i) to  register  or  qualify  all
         Registrable   Securities   and  other   securities   covered   by  such
         registration  statement under such other securities or blue sky laws of
         such States of the United  States of America  where an exemption is not
         available and as the sellers of Registrable  Securities covered by such
         registration  statement  shall  reasonably  request,  (ii) to keep such
         registration   or   qualification   in  effect  for  so  long  as  such
         registration  statement remains in effect,  and (iii) to take any other
         action  which may be  reasonably  necessary or advisable to enable such
         sellers to consummate  the  disposition  in such  jurisdictions  of the
         securities  to be sold by such  sellers,  except that the Company shall
         not for any  such  purpose  be  required  to  qualify  generally  to do
         business as a foreign corporation in any jurisdiction  wherein it would
         not but for the requirements of this subdivision (d) be obligated to be
         so  qualified  or to consent to general  service of process in any such
         jurisdiction;

                  (e) use its best efforts to cause all  Registrable  Securities
         covered  by  such  registration  statement  to be  registered  with  or
         approved  by such  other  Federal  or state  governmental  agencies  or
         authorities  as may be  necessary  in the  opinion  of  counsel  to the
         Company and counsel to the seller or sellers of Registrable  Securities
         to enable the seller or sellers  thereof to consummate the  disposition
         of such Registrable Securities;

                  (f) furnish to each seller of Registrable  Securities a signed
         counterpart  of (i) an opinion of  independent  counsel for the Company
         and  (ii)  a  "comfort"   letter  signed  by  the  independent   public
         accountants  who have  certified  the  Company's  financial  statements
         included or incorporated by reference in such  registration  statement,
         covering   substantially   the  same   matters  with  respect  to  such
         registration  statement (and the prospectus included therein),  and, in
         the case of the  accountants'  comfort  letter,  with respect to events
         subsequent to the date of such financial statements, as are customarily
         covered in  opinions of issuer's  counsel and in  accountants'  comfort
         letters delivered to the underwriters in underwritten  public offerings
         of securities  (and dated the dates such  opinions and comfort  letters
         are  customarily  dated) and, in the case of the  accountants'  comfort
         letters,  such other financial  matters,  and, in the case of the legal
         opinion,  such other legal matters,  as the sellers of more than 50% of
         the Registrable  Securities  covered by such registration  statement or
         the underwriters may reasonably request;

                  (g) notify each seller of  Registrable  Securities  covered by
         such  registration  statement  at any time when a  prospectus  relating
         thereto is required to be  delivered  under the  Securities  Act,  upon
         discovery  that,  or upon the  happening  of any  event as a result  of
         which, the prospectus included in such registration  statement, as then
         in effect,  includes an untrue statement of a material fact or omits to
         state any material fact  required to be stated  therein or necessary to
         make  the  statements  therein  not  misleading,  in the  light  of the
         circumstances  under  which they were made,  and at the  request of any
         such seller promptly  prepare and furnish to it a reasonable  number of
         copies of a supplement to or an amendment of such  prospectus as may be
         necessary so that,  as thereafter  delivered to the  purchasers of such
         securities,  such prospectus shall not include an untrue statement of a
         material  fact or omit to state a material  fact  required to be stated
         therein or necessary to make the  statements  therein not misleading in
         the light of the circumstances under which they were made;

                  (h)  otherwise  use  its  best  efforts  to  comply  with  all
         applicable rules and regulations of the Commission,  and make available
         to its security holders, as soon as reasonably practicable, an earnings
         statement  covering the period of at least twelve months,  but not more
         than eighteen  months,  beginning  with the first full  calendar  month
         after the effective date of such registration statement, which earnings
         statement  shall  satisfy  the  provisions  of  Section  11(a)  of  the



         Securities Act, and promptly furnish to each such seller of Registrable
         Securities a copy of any amendment or  supplement to such  registration
         statement or prospectus;

                  (i) provide and cause to be  maintained  a transfer  agent and
         registrar (which, in each case, may be the Company) for all Registrable
         Securities covered by such registration statement from and after a date
         not later than the effective date of such registration; and

                  (j) use its best  efforts to list all  Registrable  Securities
         covered  by such  registration  statement  on any  national  securities
         exchange  on which  Registrable  Securities  of the same class and,  if
         applicable,  series,  covered by such  registration  statement are then
         listed.

The Company may require each seller of  Registrable  Securities  as to which any
registration is being effected to furnish the Company such information regarding
such seller and the distribution of such securities as the Company may from time
to time reasonably request in writing.

         Each holder of  Registrable  Securities  agrees by  acquisition of such
Registrable  Securities  that upon receipt of any notice from the Company of the
happening of any event of the kind described in subdivision  (g) of this Section
2.3,  such  holder will  forthwith  discontinue  such  holder's  disposition  of
Registrable  Securities pursuant to the registration  statement relating to such
Registrable  Securities  until  such  holder's  receipt  of  the  copies  of the
supplemented  or amended  prospectus  contemplated  by  subdivision  (g) of this
Section 2.3 and, if so directed by the Company,  will deliver to the Company (at
the Company's  expense) all copies,  other than permanent  file copies,  then in
such  holder's  possession  of  the  prospectus  relating  to  such  Registrable
Securities current at the time of receipt of such notice.

         2.4 Underwritten  Offerings.  (a) Requested Underwritten  Offerings. If
requested  by the  underwriters  for any  underwritten  offering  by  holders of
Registrable  Securities pursuant to a registration  requested under Section 2.1,
the Company will enter into an underwriting agreement with such underwriters for
such  offering,  such agreement to be reasonably  satisfactory  in substance and
form to the Company,  each such holder and the  underwriters and to contain such
representations  and  warranties  by the  Company  and such  other  terms as are
generally prevailing in agreements of that type, including,  without limitation,
indemnities to the effect and to the extent provided in Section 2.7. The holders
of the Registrable  Securities  proposed to be distributed by such  underwriters
will  cooperate  with  the  Company  in  the  negotiation  of  the  underwriting
agreement.  Such  holders  of  Registrable  Securities  shall be parties to such
underwriting  agreement and may, at their option, require that any or all of the
representations  and warranties by, and the other agreements on the part of, the
Company to and for the  benefit of such  underwriters  shall also be made to and
for the benefit of such holders of Registrable Securities and that any or all of
the  conditions  precedent to the  obligations of such  underwriters  under such
underwriting  agreement  on  conditions  precedent  to the  obligations  of such
holders of Registrable  Securities.  Any such holder of  Registrable  Securities
shall not be required to make any representations or warranties to or agreements
with the Company other than representations,  warranties or agreements regarding
such holder,  such holder's  Registrable  Securities and such holder's  intended
method of distribution and any other representation required by law.

         (b)  Incidental  Underwritten  Offerings.  If the  Company  proposes to
register any of its  securities  under the  Securities  Act as  contemplated  by
Section 2.2 and such  securities are to be distributed by or through one or more
underwriters,  the  Company  will,  subject to Sections  2.2 and 2.9 hereof,  if
requested  by any  Requesting  Holder  of  Registrable  Securities  use its best
efforts  to  arrange  for  such  underwriters  to  include  all the  Registrable
Securities to be offered and sold by such Requesting Holder among the securities
of  the  Company  to  be  distributed  by  such  underwriters.  The  holders  of
Registrable  Securities to be distributed by such underwriters  shall be parties
to the underwriting agreement between the Company and such underwriters and may,
at their option,  require that any or all of the  representations and warranties
by, and the other  agreements on the part of, the Company to and for the benefit



of such  underwriters  shall also be made to and for the benefit of such holders
of Registrable Securities and that any or all of the conditions precedent to the
obligations of such underwriters under such underwriting agreement be conditions
precedent to the obligations of such holders of Registrable Securities. Any such
Requesting  Holder of Registrable  Securities  shall not be required to make any
representations  or  warranties  to  or  agreements  with  the  Company  or  the
underwriters other than representations, warranties or agreements regarding such
Requesting  Holder,  such Requesting  Holder's  Registrable  Securities and such
Requesting  Holder's intended method of distribution or as otherwise required by
law.

         2.5.  Preparation;  Reasonable  Investigation.  In connection  with the
preparation and filing of each  registration  statement under the Securities Act
pursuant  to this  Agreement  the Company  will give the holders of  Registrable
Securities registered under such registration statement, their underwriters,  if
any, and their respective counsel and accountants the opportunity to participate
in the preparation of such  registration  statements,  each prospectus  included
therein or filed with the  Commission,  and,  to the  extent  practicable,  each
amendment  thereof or supplement  thereto,  and give each of them such access to
its books and records (to the extent  customarily  given to the  underwriters of
the Company's  securities),  such  opportunities  to discuss the business of the
Company  with its  officers  and the  independent  public  accountants  who have
certified its financial statements as shall be necessary, in the opinion of such
holders'  and such  underwriters'  respective  counsel,  to conduct a reasonable
investigation within the meaning of the Securities Act.

         2.6.  Limitations,  Conditions and  Qualifications to Obligations under
Registration  Covenants.  The  obligations  of the Company to use its reasonable
efforts  to  cause  the  Registrable  Securities  to  be  registered  under  the
Securities Act are subject to each of the following limitations,  conditions and
qualifications:

         (a)  The  Company  shall  not be  obligated  to file  any  registration
statement  pursuant to Section  2.1 hereof at any time if the  Company  would be
required to include financial  statements  audited as of any date other than the
end of its fiscal year.

         (b) The Company  shall be entitled to postpone for a reasonable  period
of time (but not  exceeding  60 days) the filing of any  registration  statement
otherwise required to be prepared and filed by it pursuant to Section 2.1 if the
Company  determines,  in its reasonable  judgment,  that such  registration  and
offering   would   interfere   with  any   financing,   acquisition,   corporate
reorganization or other material transaction involving the Company or any of its
Affiliates or would require premature  disclosure thereof and promptly gives the
holders of Registrable  Securities  requesting  registration thereof pursuant to
Section 2.1 written notice of such determination, containing a general statement
of the reasons for such  postponement  and an  approximation  of the anticipated
delay. If the Company shall so postpone the filing of a registration  statement,
such holders of Registrable Securities requesting  registration thereof pursuant
to Section 2.1 shall have the right to withdraw the request for  registration by
giving  written notice to the Company within 30 days after receipt of the notice
of postponement and, in the event of such withdrawal,  such request shall not be
counted for  purposes  of the  requests  for  registration  to which  holders of
Registrable Securities are entitled pursuant to Section 2.1 hereof.

         (c) (i)  Holders of  Registrable  Securities  shall use all  reasonable
efforts  to effect as wide a  distribution  of such  Registrable  Securities  as
reasonably  practicable  (and the holders of such  Registrable  Securities shall
secure the  agreement of their  underwriter  or  underwriters,  if any, for such
offering  to  comply  with the  foregoing),  and (ii)  except  with  respect  to
underwritten  offerings pursuant hereto, holders of Registrable Securities shall
use  their  best  efforts  (which  shall  include  advising  any  broker  of the
provisions of this Section 2.6(c) but shall not require undue  investigation  on
the part of any such  holder) so that in no event shall any sale of  Registrable
Securities be made  knowingly to any Person  (including  its  Affiliates) or any
Person  or  entities  which  are to the  knowledge  of such  holders  (or to the
knowledge  of any  underwriter  for such  holders)  part of any 13D Group  which



includes such  purchaser or any of its  Affiliates),  that, in each case,  after
giving  effect  to  such  sale,  would   Beneficially   Own  Voting   Securities
representing more than 10% of the Total Voting Power.

         2.7. Indemnification.  (a) Indemnification by the Company. In the event
of any  registration  of any securities of the Company under the Securities Act,
the Company will, and hereby does,  indemnify and hold harmless,  in the case of
any registration  statement filed pursuant to Section 2.1 or 2.2, each seller of
any  Registrable  Securities  covered  by  such  registration   statement,   its
directors,  officers,  partners, agents and affiliates and each other Person who
participates  as an underwriter  in the offering or sale of such  securities and
each other  Person,  if any,  who controls  such seller or any such  underwriter
within the meaning of the Securities Act, against any losses, claims, damages or
liabilities,  joint or  several,  to which  such  seller  or any such  director,
officer,  partner,  agent or affiliate or underwriter or controlling  Person may
become  subject under the  Securities  Act or otherwise  insofar as such losses,
claims, damages or liabilities (or actions or proceedings,  whether commenced or
threatened,  in  respect  thereof)  arise  out of or are based  upon any  untrue
statement or alleged  untrue  statement of any  material  fact  contained in any
registration  statement under which such  securities  were registered  under the
Securities  Act,  any  preliminary  prospectus,   final  prospectus  or  summary
prospectus  contained therein,  or any amendment or supplement  thereto,  or any
omission or alleged  omission to state  therein a material  fact  required to be
stated  therein  or  necessary  to make the  statements  therein in light of the
circumstances  in which  they were made not  misleading,  and the  Company  will
reimburse  such  seller  and each  such  director,  officer,  partner,  agent or
affiliate,  underwriter  and  controlling  Person  for any  legal  or any  other
expenses  reasonably  incurred  by  them in  connection  with  investigating  or
defending any such loss, claim, liability, action or proceeding;  provided, that
the  Company  shall not be liable in any such case to the  extent  that any such
loss, claim,  damage,  liability (or action or proceeding in respect thereof) or
expense  arises out of or is based upon an untrue  statement  or alleged  untrue
statement or omission or alleged omission made in such  registration  statement,
any such preliminary prospectus, final prospectus, summary prospectus, amendment
or  supplement  in reliance  upon and in  conformity  with  written  information
furnished to the Company  through an instrument duly executed by or on behalf of
such seller or underwriter,  as the case may be, specifically stating that it is
for use in the preparation  thereof;  and, provided,  further,  that the Company
shall not be liable to any  Person who  participates  as an  underwriter  in the
offering or sale of  Registrable  Securities  or any other  Person,  if any, who
controls such underwriter  within the meaning of the Securities Act, in any such
case to the extent that any such loss,  claim,  damage,  liability (or action or
proceeding in respect  thereof) or expenses arises out of such Person's  failure
to  send  or  give a copy  of the  final  prospectus,  as the  same  may be then
supplemented or amended,  to the Person asserting an untrue statement or alleged
untrue  statement  or  omission  or alleged  omission at or prior to the written
confirmation  of the  sale of  Registrable  Securities  to such  Person  if such
statement or omission  was  corrected in the final  prospectus.  Such  indemnity
shall remain in full force and effect regardless of any investigation made by or
on  behalf of such  seller  or any such  director,  officer,  partner,  agent or
affiliate  or  controlling  person  and  shall  survive  the  transfer  of  such
securities by such seller.

         (b)  Indemnification  by the Sellers.  As a condition to including  any
Registrable  Securities in any  registration  statement,  the Company shall have
received an undertaking  satisfactory to it from the prospective  seller of such
Registrable  Securities,  to indemnify and hold harmless (in the same manner and
to the same  extent as set forth in  subdivision  (a) of this  Section  2.7) the
Company, and each director of the Company,  each officer of the Company and each
other  Person,  if any,  who  controls  the  Company  within the  meaning of the
Securities  Act,  with  respect  to any  statement  or alleged  statement  in or
omission or alleged omission from such registration  statement,  any preliminary
prospectus,  final prospectus or summary prospectus  contained  therein,  or any
amendment or  supplement  thereto,  if such  statement  or alleged  statement or
omission or alleged  omission was made in reliance upon and in  conformity  with
written information furnished to the Company through an instrument duly executed
by such seller  specifically  stating that it is for use in the  preparation  of



such registration statement,  preliminary prospectus, final prospectus,  summary
prospectus,  amendment or supplement.  Such indemnity shall remain in full force
and effect,  regardless of any investigation made by or on behalf of the Company
or any such  director,  officer  or  controlling  person and shall  survive  the
transfer of such securities by such seller.

         (c) Notices of Claims,  etc.  Promptly  after receipt by an indemnified
party or notice of the  commencement  of any action or  proceeding  involving  a
claim  referred to in the  preceding  subdivisions  of this  Section  2.7,  such
indemnified  party will, if a claim in respect  thereof is to be made against an
indemnifying  party,  give written notice to the latter of the  commencement  of
such action;  provided, that the failure of any indemnified party to give notice
as provided herein shall not relieve the  indemnifying  party of its obligations
under the preceding  subdivisions of this Section 2.7, except to the extent that
the indemnifying party is actually materially prejudiced by such failure to give
notice.  In case any such  action is brought  against an  indemnified  party the
indemnifying  party  shall be  entitled to  participate  in and,  unless in such
indemnified  party's  reasonable  judgment a conflict of interest  between  such
indemnified  and  indemnifying  parties may exist in respect of such  claim,  to
assume the defense thereof,  jointly with any other indemnifying party similarly
notified to the extent that it may wish, with counsel reasonably satisfactory to
such indemnified  party,  and after notice from the  indemnifying  party to such
indemnified  party  of its  election  so to  assume  the  defense  thereof,  the
indemnifying  party shall not be liable to such indemnified  party for any legal
or other  expenses  subsequently  incurred by the latter in connection  with the
defense thereof other than reasonable costs of investigation; provided, however,
that all  indemnified  parties  with  respect to a claim shall have the right to
employ one  separate  counsel in  connection  with  their  participation  in the
defense of such claim and the fees and expenses of such counsel shall be paid by
the  indemnifying  party if,  but only if, in the  reasonable  judgment  of such
indemnified  parties,  based upon the written  advice of counsel,  a conflict of
interest exists between such indemnified parties and the indemnifying party with
respect to such claim. An  indemnifying  party who does not elect to participate
in the defense of a claim, together with all other indemnifying  parties,  shall
not be  obligated  to pay the fees and expenses of more than one counsel for all
indemnified  parties with respect to any such claim. No indemnifying party shall
be liable for any  settlement of any action or proceeding  effected  without its
written  consent.  No  indemnifying  party  shall,  without  the  consent of the
indemnified party, consent to entry of any judgment or enter into any settlement
which  does not  include  as an  unconditional  term  thereof  the giving by the
claimant or plaintiff to such indemnified  party of a release from all liability
in respect to such claim or litigation.

         (d) Contribution.  If the indemnification  provided for in this Section
2.7 shall for any reason be held by a court to be  unavailable to an indemnified
party under subparagraph (a) or (b) hereof in respect of any loss, claim, damage
or liability, or any action in respect thereof, then, in lieu of the amount paid
or payable under  subparagraph (a) or (b) hereof,  the indemnified party and the
indemnifying  party under subparagraph (a) or (b) hereof shall contribute to the
aggregate  losses,  claims,  damages and liabilities  (including  legal or other
expenses  reasonably incurred in connection with investigating the same), (i) in
such  proportion as is  appropriate to reflect the relative fault of the Company
and  the  prospective   sellers  of  Registrable   Securities   covered  by  the
registration  statement which resulted in such loss, claim, damage or liability,
or action in respect thereof,  with respect to the statements or omissions which
resulted in such loss, claim, damage or liability, or action in respect thereof,
as well as any other relevant equitable considerations or (ii) if the allocation
provided  by clause  (i)  above is not  permitted  by  applicable  law,  in such
proportion as shall be appropriate to reflect the relative  benefits received by
the Company and such  prospective  sellers from the  offering of the  securities
covered  by  such  registration   statement.  No  Person  guilty  of  fraudulent
misrepresentation  (within the meaning of Section 11(f) of the  Securities  Act)
shall be  entitled  to  contribution  from any Person who was not guilty of such
fraudulent   misrepresentation.   Such  prospective   sellers'   obligations  to
contribute as provided in this subparagraph (d) are several in proportion to the
relative  value of  their  respective  Registrable  Securities  covered  by such
registration  statement and not joint. In addition, no Person shall be obligated



to contribute  hereunder any amounts in payment for any settlement of any action
or claim  effected  without such  Person's  consent,  which consent shall not be
unreasonably withheld.

         (e) Other Indemnification.  Indemnification and contribution similar to
that  specified  in the  preceding  subparagraphs  of  this  Section  2.7  (with
appropriate  modifications)  shall be given by the  Company  and each  seller of
Registrable  Securities  with  respect  to any  required  registration  or other
qualification  of securities under any Federal or state law or regulation of any
governmental authority other than the Securities Act.

         (f)  Indemnification  Payments.  The  indemnification  and contribution
required by this  Section  2.7 shall be made by periodic  payments of the amount
thereof during the course of the investigation or defense, as and when bills are
received or expense, loss, damage or liability is incurred.

         2.8. Adjustment Affecting Registrable Securities.  The Company will not
effect  or  permit  to occur  any  combination  or  subdivision  of  Registrable
Securities which would materially adversely affect the ability of the holders of
Registrable   Securities   to  include  such   Registrable   Securities  in  any
registration   of  its  securities   contemplated  by  this  Section  2  or  the
marketability of such Registrable Securities under any such registration.

         2.9.   Conditions  and  Limitations  on  Registrations  of  Registrable
Securities.  (a) The Company shall not be required to effect any registration of
Registrable Securities pursuant to this Section 2 until after October 4, 1997 or
at any time that all Registrable  Securities held by any holders requesting such
registration  can be  transferred  by such  holders  under  Rule 144  under  the
Securities Act within 183 days from the date of such request for registration.

         (b) The Company  shall not be required  to effect any  registration  of
Registrable Securities pursuant to Section 2.2 hereof if it shall deliver to the
holder or holders  requesting  such  registration  an opinion of counsel  (which
opinion and counsel shall be reasonably  satisfactory to such holder or holders)
to the effect that the Registrable  Securities requested to be registered may be
sold by such  holder in the  manner,  time  period and volume  intended  by such
holder without registration under the Securities Act.

         (c) The registration  rights provided by this Section 2 shall terminate
upon the tenth anniversary of the date hereof.

         2.10.  Certain  Rights  of  an  Investor  If  Named  in a  Registration
Statement.  If any statement  contained in a  registration  statement  under the
Securities  Act refers to an Investor by name or  otherwise as the holder of any
securities of the Company,  then such  Investor  shall have the right to require
(i) the  insertion  therein  of  language,  in  form  and  substance  reasonably
satisfactory to such Investor and the Company, to the effect that the holding by
such  Investor of such  securities  does not  necessarily  make such  Investor a
"controlling person" of the Company within the meaning of the Securities Act and
is not to be construed as a  recommendation  by such Investor of the  investment
quality of the Company's debt or equity securities covered thereby and that such
holding  does not imply that such  Investor  will  assist in meeting  any future
financial  requirements  of the Company or (ii) in the event that such reference
to such Investor by name or otherwise is not required by the  Securities  Act or
any of the rules and  regulations  promulgated  thereunder,  the deletion of the
reference to such Investor.

         3. Definitions.  As used herein, unless the context otherwise requires,
the following terms have the following respective meanings:

         "Commission" means the Securities and Exchange  Commission or any other
Federal agency at the time administering the Securities Act.

         "Exchange Act" means the  Securities  Exchange Act of 1934, as amended,
or any similar Federal statute,  and the rules and regulations of the Commission
thereunder,  all as the same  shall be in  effect at the  time.  Reference  to a
particular  section of the  Securities  Exchange Act of 1934, as amended,  shall
include a reference  to the  comparable  section,  if any,  of any such  similar
Federal statute.




         "Person"  means  a  corporation,  an  association,  a  partnership,  an
unincorporated organization, a joint venture, a joint stock company, a trust, an
individual,  a government or a department  or agency of a  government,  or other
entity.

         "Registrable  Securities"  means (i) the Shares and the Warrant  Shares
held  from  time  to time by the  Investors  or any  Person  to  whom  any  such
securities  have been  transferred  in  accordance  with  Section  5.2(c) of the
Purchase Agreement  ("Permitted Holders") and (ii) any securities of the Company
(including,  without limitation,  the Rights) issued or issuable with respect to
any  shares  of Common  Stock by way of a stock  dividend  or stock  split or in
connection with a combination of shares, recapitalization, merger, consolidation
or  other  reorganization  or  otherwise.   As  to  any  particular  Registrable
Securities, once issued such securities shall cease to be Registrable Securities
when (a) a registration  statement  with respect to the sale of such  securities
shall have become  effective under the Securities Act and such securities  shall
have been disposed of in accordance with such registration  statement,  (b) they
shall have been sold as permitted by Rule 144 (or any successor provision) under
the  Securities  Act,  (c) they  shall  have  been  otherwise  transferred,  new
certificates  for them not bearing a legend  restricting  further transfer shall
have been delivered by the Company and subsequent  public  distribution  of them
shall not require  registration  of them under the  Securities  Act, or (d) they
shall have ceased to be outstanding.

         "Registration  Expenses"  means all expenses  incident to the Company's
performance of or compliance with Section 2, including,  without limitation, all
registration,  filing and NASD fees,  all fees and  expenses of  complying  with
securities  or blue sky laws,  all word  processing,  duplicating  and  printing
expenses, messenger and delivery expenses, the fees and disbursements of counsel
for  the  Company  and of its  independent  public  accountants,  including  the
expenses of "cold comfort"  letters  required by or incident to such performance
and compliance,  any fees and disbursements of underwriters  customarily paid by
issuers or sellers of securities and, in the case of a registration  pursuant to
Sections 2.1 and 2.2, the reasonable  fees and expenses of one counsel to all of
the Selling Holders  (selected by Selling  Holders  representing at least 50% of
the Registrable  Securities covered by such  registration);  provided,  however,
that  Registration  Expenses  shall  exclude and the sellers of the  Registrable
Securities  shall pay the fees and  disbursements  of counsel and accountants to
such sellers and  underwriting  discounts and  commissions and transfer taxes in
respect of the Registrable Securities being registered,  except that in the case
of a  registration  pursuant to Sections 2.1 and 2.2, the Company  shall pay the
reasonable fees and expenses of one counsel to the Selling Holders  (selected by
Selling Holders representing at least 50% of the Registrable  Securities covered
by such registration).

         "Securities  Act" means the Securities Act of 1933, as amended,  or any
similar  Federal  statute,  and  the  rules  and  regulation  of the  Commission
thereunder,  all as the same  shall be in effect at the  time.  References  to a
particular  section of the  Securities  Act of 1933 shall include a reference to
the comparable section, if any, of any such similar Federal statute.

         4. Rule 144. The Company shall take all actions reasonably necessary to
enable  holders  of  Registrable  Securities  to sell  such  Securities  without
registration  under the  Securities  Act within the limitation of the exemptions
provided by (a) Rule 144 under the  Securities  Act, as such Rule may be amended
from time to time,  or (b) any similar rule or regulation  hereafter  adopted by
the  Commission  including,  without  limiting the  generality of the foregoing,
filing on a timely basis all reports  required to be filed by the Exchange  Act.
Upon the  request of any holder of  Registrable  Securities,  the  Company  will
deliver to such holder a written  statement as to whether it has  complied  with
such requirements.




         5. Amendments and Waivers.  This Agreement may be amended only with the
written  consent of the  Company  and the  Company  may take any  action  herein
prohibited,  or omit to perform any act herein  required to be  performed by it,
only if the Company shall have obtained the written  consent to such  amendment,
action or omission  to act, of the holder or holders of at least  66-2/3% of the
Registrable Securities. Each holder of any Registrable Securities at the time or
thereafter  outstanding shall be bound by any consent authorized by this Section
5, whether or not such Registrable Securities shall have been marked to indicate
such consent.

         6. Nominees for Beneficial  Owners.  In the event that any  Registrable
Securities  are  held  by a  nominee  for  the  beneficial  owner  thereof,  the
beneficial  owner  thereof  may,  at its  election in writing  delivered  to the
Company, be treated as the holder of such Registrable Securities for purposes of
any request or other action by any holder or holders of  Registrable  Securities
pursuant to this Agreement or any  determination  of any number or percentage of
shares or  Registrable  Securities  held by any holder or holders of Registrable
Securities  contemplated  by this  Agreement.  If the  beneficial  owner  of any
Registrable  Securities so elects, the Company may require assurances reasonably
satisfactory  to it of such owner's  beneficial  ownership  of such  Registrable
Securities.

         7. Notices. All communications  provided for hereunder shall be sent by
postage-prepaid  first-class  mail,  shall be deemed to be  received  three days
after  being  sent,  or, if earlier,  the date of actual  receipt,  and shall be
addressed as follows:

         (a) if to any  Investor,  addressed to such  Investor in the manner set
forth in the Purchase Agreement, or at such other address as such Investor shall
have furnished to the Company in writing;

         (b) if to any other holder of  Registrable  Securities,  at the address
that such holder shall have  furnished to the Company in writing,  or, until any
such other  holder so  furnishes  to the Company an address,  then to and at the
address of the last holder of such  Registrable  Securities who has furnished an
address to the Company; or

         (c) if to the  Company,  addressed to it in the manner set forth in the
Purchase Agreement, or at such other address as the Company shall have furnished
to each holder of Registrable Securities at the time outstanding.

         8.  Assignment;  Calculation  of  Percentage  Interests in  Registrable
Securities. (a) This Agreement shall be binding upon and inure to the benefit of
and be enforceable  by the parties hereto and, with respect to the Company,  its
respective successors and assigns and, with respect to the Investors, any holder
of any Registrable Securities,  subject to the provisions respecting the minimum
numbers of percentages of shares of Registrable  Securities required in order to
be entitled to certain rights, or take certain actions,  contained  herein.  The
Investors  named in the first  paragraph  of this  Agreement  (and not any other
holder of  Registrable  Securities or any other  Person) shall be permitted,  in
connection with a transfer or disposition of Registrable Securities permitted by
the Purchase  Agreement,  to impose  conditions or constraints on the ability of
the transferee, as a holder of Registrable Securities, to request a registration
pursuant  to Section  2.1 and shall  provide  the  Company  with  copies of such
conditions or constraints and the identity of such transferees.

         (b) For the purposes of this Agreement,  all references to a percentage
of the  Registrable  Securities  shall be  calculated  based  upon the number of
shares of Registrable  Securities  outstanding  at the time such  calculation is
made assuming the issuance of all Warrant Shares.

         9. Descriptive  Headings.  The descriptive headings of the sections and
paragraphs of this Agreement are inserted for reference only and shall not limit
or otherwise affect the meaning hereof.

         10.  Governing Law. This  Agreement  shall be construed and enforced in
accordance with, and the rights of the parties shall be governed by, the laws of
the State of Delaware.




         11.  Counterparts.  This  Agreement  may be  executed  in any number of
counterparts,  each  of  which  shall  be  deemed  an  original,  but  all  such
counterparts shall together constitute one and the same instrument.

         IN WITNESS  THEREOF,  the  parties  have caused  this  Agreement  to be
executed and delivered by their respective officers thereunto duly authorized as
of the date first above written.


                                   /s/  G.S. Beckwith Gilbert
                                  --------------------------
                                   G.S. Beckwith Gilbert



                                   GILBERT FAMILY TRUST


                                   By  /s/ G. S. Beckwith Gilbert
                                      ------------------------------
                                       Name: G. S. Beckwith Gilbert
                                       Title:Trustee



                                   G.S. BECKWITH GILBERT I.R.A. CONTRIBUTORY
                                   ACCOUNT


                                   By /s/ G. S. Beckwith Gilbert
                                     -----------------------------
                                       Name:  G.S. Beckwith Gilbert
                                       Title:Trustee



                                   DIANON SYSTEMS, INC.


                                   By  /s/ Richard A. Sandberg
                                     ---------------------------
                                       Name: Richard A. Sandberg
                                       Title:President, Chairman and
                                             Chief Executive Officer