REGISTRATION RIGHTS AGREEMENT

        THIS REGISTRATION  RIGHTS AGREEMENT  ("Agreement") is entered into as of
___________,  1996, by and among  CELGENE  CORPORATION,  a Delaware  corporation
("Company"),  Swartz  Investments,  LLC,  a Georgia  limited  liability  company
("Swartz  Investments")  and the  subscribers  ("Subscribers")  to the Company's
offering  ("Offering")  of up to $15 million of Series A  Convertible  Preferred
Stock (the "Preferred Stock") pursuant to the Subscription Agreement between the
Company and the Subscribers ("Subscription Agreement").

        1. Definitions. For purposes of this Agreement:

        (a) The term "register",  "registered,"  and  "registration"  refer to a
registration  effected  by  preparing  and filing a  registration  statement  or
similar document in compliance with the Securities Act of 1933 (the "Act"),  and
the declaration or ordering of effectiveness of such  registration  statement or
document;

        (b) The term "Registrable Securities" means the Common Stock issuable or
issued upon (i)  conversion  of the  Preferred  Stock issued to Investors in the
Offering,  (ii)  exercise  of the Lockup  Warrants,  and (iii)  exercise  of the
Warrant(s);

        (c) The number of shares of "Registrable  Securities  then  outstanding"
shall be  determined  by the  number of shares of Common  Stock  which have been
issued or are issuable upon  conversion  of the Preferred  Stock and exercise of
the Warrants and Lock Up Warrants at the time of such determination;

        (d) The term  "Holder"  means any  person  owning or having the right to
acquire Registrable Securities or any permitted assignee thereof;

        (e) The term "Warrants" means the warrants granted to Swartz Investments
or to  persons  designated  by Swartz  Investments  in  connection  with i) this
Offering and ii) the offering by the Company,  through Swartz Investments,  Inc.
of the Company's 8% Convertible Debentures Due July 31, 1997;

        (f) The term "Lockup  Warrants"  means the "90 Day Lockup  Warrants" and
the "180 Day Lockup  Warrants",  as those  terms are defined in  Certificate  Of
Designation of Series A Convertible Preferred Stock of Celgene Corporation; and

        (g)  The  term   "Initiating   Holders"  means  holders  of  Registrable
Securities  obtained  or  obtainable  upon  conversion  of at least four hundred
(400) shares of Preferred Stock.

        2. Required Registration.

        (a) Within 30 days after the Last Closing of the Offering (as defined in
the  Subscription  Agreement),  but in no event  sooner  than April 10, 1996 the
Company shall

                                       1



 


file a registration statement  ("Registration  Statement") on Form S-3 (or other
suitable  form,  at the  Company's  discretion  but  subject  to the  reasonable
approval of the  Investors),  covering  the resale of all shares of  Registrable
Securities then outstanding.

        (b) The Registration  Statement shall be done as a "shelf"  registration
statement under Rule 415, and shall be maintained  effective until completion of
the distribution described therein or such time as  all  Registrable  Securities
covered thereby can be immediately sold without any limitation  on  volume.  The
Company shall use its best efforts to have the  Registration  Statement declared
effective  within 90 days after the Last Closing (as defined in the Subscription
Agreement)  (the date which is 90 days after the Last Closing herein referred to
as the "Due Date").

        (c) If the Registration  Statement is not declared  effective by the Due
Date,  the Company must continue to use its best efforts to obtain a declaration
of  effectiveness  and shall pay the Investors an amount equal to one and a half
percent (1 1/2%) per month of the  aggregate  amount of Preferred  Stock sold in
the Offering,  compounded  monthly,  and accruing  daily,  for the first six (6)
months and one percent (1%)  thereafter,  payable in common stock,  which common
stock  shall also be deemed  "Registrable  Securities"  for the  purpose of this
Agreement.  Provided, however, that such additional amounts shall not be payable
for so long as any delay in the  effectiveness of the Registration  Statement is
due,  directly  to causes  that are beyond the control of the Company, including
but not limited to acts of God, acts or omissions of the Agent or the Investors,
acts or omissions of  any  government  or  regulatory  body  (whether  civil  or
military)  that  result  in  a  delay  of  the  declaration  by  the  SEC of the
effectiveness of registration  statements generally,  fires, explosions, floods,
earthquakes  or  other  natural or man-made  disasters,  epidemics, wars, riots,
civil  disturbances,  sabotage,  strikes, lockouts, labor difficulties involving
third  parties,  loss  of  electrical  or  other  power,  or  telecommunications
equipment or line failures.

        3. Demand Registration.

        (a) If the  Registration  Statement  described in Section 2 above is not
effective by the Due Date,  Initiating Holders may notify the Company in writing
and demand that the Company file a registration  statement  under the Securities
Act (a "Demand  Registration  Statement") covering the resale of the Registrable
Securities then outstanding  held by such Holders.  Upon receipt of such notice,
the Company shall, within ten (10) days thereafter,  give written notice of such
request to all Holders and shall, subject to the limitations of subsection 3(b),
as soon as  practicable,  and in any event  within 60 days after the  receipt of
such  request,  include in the Demand  Registration  Statement  all  Registrable
Securities which the Holders request, by notice given to the Company within (10)
days of receipt of the Company's notice.

        (b) If the  Initiating  Holders  intend to  distribute  the  Registrable
Securities  covered by their request by means of an underwriting,  they shall so
advise the Company as a part of their  request  made  pursuant to this Section 3
and the Company shall include such information in the written notice referred to
in subsection  3(a). In such event, the

                                       2



 


right  of any  other  Holder  to  include  his  Registrable  Securities  in such
registration  shall be  conditioned  upon such  Holder's  participation  in such
underwriting  and the inclusion of such Holder's  Registrable  Securities in the
underwriting  (unless otherwise mutually agreed by a majority in interest of the
Initiating  Holders and such Holder) to the extent provided herein.  All Holders
proposing  to  distribute  their  securities  through  such  underwriting  shall
(together  with the  Company  as  provided  in  subsection  6(f))  enter into an
underwriting  agreement in customary form with the  underwriter or  underwriters
selected  for such  underwriting  by a majority in  interest  of the  Initiating
Holders,  and  reasonably  acceptable  to the  Company.  The Holder  will not be
required  to make  any  representation  other  than as to its  ownership  of the
Registrable Securities and its intended method of distribution.

        (c) The  Company is  obligated  to effect  only one demand  registration
pursuant to Section 3 of this Agreement.  The  Company  agrees  to  include  all
Registrable  Securities  held  by  all  Holders in such  Registration  Statement
without cutback or reduction. In the event the Company  breaches its  obligation
of the preceding sentence,  any Holders of the Registrable Securities which were
not included in such Registration Statement shall be entitled to such  a  second
demand  registration for such excluded securities and  the  Company  shall  keep
such registration statement effective as required by Section 6.

        The Company is not obligated to effect a demand  registration under this
Section 3 if in the opinion of counsel to the Company  reasonably  acceptable to
the  person or persons  from whom  written  request  for  registration  has been
received  (and  satisfactory  to the  Company's  transfer  agent to  permit  the
transfer)  that  registration  under the Act is not required  for the  immediate
transfer  of all of the  Registrable  Securities  pursuant  to Rule 144 or other
applicable  provision.  Such  opinion  shall be  addressed  to the Holder at the
Holder's Request.

        4. Piggyback  Registration.  If the Registration  Statement described in
Section  2 is not  effective  by  the  Due  Date,  and no  demand  for a  Demand
Registration  Statement has been made pursuant to Section 3, and if (but without
any  obligation to do so) the Company  proposes to register  (including for this
purpose a registration  effected by the Company for shareholders  other than the
Holders) any of its Common Stock under the Securities Act in connection with the
public  offering of such  securities  solely for cash (other than a registration
relating  solely for the sale of securities to  participants  in a Company stock
plan or a registration on Form S-4  promulgated  under the Securities Act or any
successor or similar form  registering  stock issuable upon a  reclassification,
upon a business  combination  involving  an  exchange of  securities  or upon an
exchange  offer for  securities  of the issuer or another  entity),  the Company
shall,  at  such  time,  promptly  give  each  Holder  written  notice  of  such
registration (a "Piggyback Registration Statement"). Upon the written request of
each  Holder  given by fax within ten (10) days after  mailing of such notice by
the Company,  which request shall state the intended  method of  disposition  of
such shares by such Holder,  the Company shall cause to be registered  under the
Securities  Act all of the  Registrable  Securities  that each such  Holder  has
requested  to be  registered.  The rights of Holders  pursuant to this Section 4
will be limited to one Piggyback  Registration  Statement and the Company is not
obligated to effect a demand registration under this Section 4 if in the opinion
of counsel to the

                                       3



 


Company reasonably acceptable to the person or persons from whom written request
for registration has been received (and  satisfactory to the Company's  transfer
agent to permit the transfer)  that  registration  under the Act is not required
for the immediate transfer of all of the Registrable Securities pursuant to Rule
144 or other applicable provision.


        5. Limitation on Obligations to Register.

        (a) In the case of a Piggyback  Registration on an  underwritten  public
offering by the Company, if the managing  underwriter  determines and advises in
writing that the  inclusion  in the  registration  statement of all  Registrable
Shares proposed to be included would interfere with the successful  marketing of
the securities proposed to be registered by the Company, then the number of such
Registrable  Shares  to be  included  in the  registration  statement  shall  be
allocated  among all Holders who had requested  Piggyback  Registration,  in the
proportion  that the  number of  Registrable  Shares  which  each  such  Holder,
including  Swartz  Investments,  seeks to register  bears to the total number of
Registrable  Shares  sought to be  included  by all  Holders,  including  Swartz
Investments;  provided  that  in  no  event  shall  the  number  of  Registrable
Securities  be less than 20% of the total  number  of  shares  included  in such
registration.

        (b)  Notwithstanding  anything to the contrary herein, the Company shall
have the right (i) to defer the initial  filing or request for  acceleration  of
effectiveness  of any Demand  Registration  Statement or Piggyback  Registration
Statement  or (ii) after  effectiveness,  to suspend  effectiveness  of any such
registration statement, if, in the good faith judgment of the board of directors
of the  Company  and upon the advice of counsel  to the  Company,  such delay in
filing  or  requesting  acceleration  of  effectiveness  or such  suspension  of
effectiveness  is  necessary in light of the  existence  of material  non-public
information  (financial or otherwise) concerning the Company disclosure of which
at the time is not, in the opinion of the board of directors of the Company upon
the advice of counsel,  (A) otherwise  required and (B) in the best interests of
the  Company;  provided  however  that the  Company  will not  delay or  suspend
effectiveness  of such  registration for more than three months from the date of
the demand,  unless it is then  engaged in an  acquisition  that would make such
registration  impracticable,  in  which  case it will use its  best  efforts  to
eliminate such impracticability as soon as possible.

                                        4



 




        6.  Obligations  of the Company. Whenever required under this Agreement
to effect the Registration of any Registrable  Securities,  the  Company  shall,
as  expeditiously  as  reasonably  possible,

        (a)  in  the  event  that  the  number   of  shares  available  under  a
registration   statement   filed  pursuant  to   Section   2   or   3  above  is
insufficient  to  cover  all  of  the  Registrable  Securities then outstanding,
based  upon  the  prior  day's  Closing  Price  (as  defined in  the Certificate
of  Designation)   of  the  Series  A  Convertible  Preferred Stock, the Company
shall   amend   that  registration   statement,  or  file  a  new   registration
statement,  or both, so as to cover all shares of  Registrable  Securities  then
outstanding.  The Company shall use its best efforts to effect such amendment or
new  registration  within 90 days of the date the  registration  statement  file
under  Section 2 or 3 is  insufficient  to cover all the  shares of  Registrable
Securities  then  outstanding.  Failure to effect an  amendment  or have the new
registration  statement declared effective within that 90 day period will result
in the Company's obligation to pay the additional amounts stated in Section 2(c)
to the Holders of Shares then outstanding, provided that such additional amounts
shall not be payable for any day for which the number of shares of Common  Stock
available under the Registration Statement, is sufficient,  based upon the prior
day's Closing Price to cover all of the Registrable Securities then outstanding.

        (b) Prepare and file with the SEC a registration  statement with respect
to  such  Registrable  Securities  and  use  its  best  efforts  to  cause  such
registration statement to become effective.

        (c) Prepare and file with the SEC such  amendments  and  supplements  to
such registration statement and  the  prospectus  used  in  connection with such
registration  statement as may be necessary to comply with the provisions of the
Act  with  respect  to  the  disposition  of  all  securities  covered  by  such
registration statement.

        (d) With respect to any Demand Registration Statement,  use best efforts
to keep such registration  statement effective until the later of 60 days  after
all shares of the Preferred Stock have  been  converted  and  all  Warrants  and
Lock-up Warrants have been exercised.


        (e)  Furnish to the  Holders  such  numbers  of copies of a  prospectus,
including a preliminary  prospectus,  in conformity with the requirements of the
Securities Act, and such other documents as they may reasonably request in order
to facilitate the disposition of Registrable Securities owned by them.

        (f) Use its best efforts to register and qualify the securities  covered
by such  registration  statement under such other securities or Blue Sky laws of
such  jurisdictions  as shall be  reasonably  requested  by the  Holders  of the
Registrable Securities covered by such registration statement, provided that the
Company shall not be required in connection  therewith or as a condition thereto
to qualify to do business or to file a general  consent to service of process in
any such states or jurisdictions.

        (g) In the event of any  underwritten  public  offering,  enter into and

                                       5



 


perform its obligations under an underwriting  agreement, in usual and customary
form, with the managing underwriter of such offering.  Each Holder participating
in such  underwriting  shall also enter into and perform its  obligations  under
such an agreement.

        (h) Furnish,  at the request of any Holder  requesting  registration  of
Registrable  Securities  pursuant  to this  Agreement,  on the  date  that  such
Registrable  Securities are delivered to the underwriters for sale in connection
with a registration  pursuant to this  Agreement,  if such  securities are being
sold through  underwriters,  or, if such  securities  are not being sold through
underwriters,  on the date that the registration  statement with respect to such
securities  becomes effective,  (i) an opinion,  dated such date, of the outside
counsel of recognized Standing (or reasonably acceptable to Holder) representing
the   Company   for  the  purposes   of   such   registration,   in   form   and
substance as is customarily  given to  underwriters  in an  underwritten  public
offering,  addressed to the underwriters,  if any, and to the Holders requesting
registration  of Registrable  Securities and (ii) a letter dated such date, from
the  independent  certified  public  accountants  of the  Company,  in form  and
substance as is customarily given by independent certified public accountants to
underwriters in an underwritten public offering,  addressed to the underwriters,
if any, and to the Holders requesting registration of Registrable Securities.

        (i) As  promptly  as  practicable  after  becoming  aware of such event,
notify  each  Investor  of the  happening  of any event of which the Company has
knowledge,  as a result of which the  prospectus  included  in the  Registration
Statement, as then in effect, includes an untrue statement of a material fact or
omits to state a material  fact  required to be stated  therein or  necessary to
make the statements therein, in light of the circumstances under which they were
made, not misleading,  and use its best efforts promptly to prepare a supplement
or amendment to the  Registration  Statement to correct such untrue statement or
omission, and deliver a number of copies of such supplement or amendment to each
Investor as such Investor may reasonably request.

        (j) Provide  Holders with written notice of the date that a registration
statement  registering  the resale of the  Registrable  Securities  is  declared
effective by the Securities and Exchange Commission ("SEC").

        (k) Provide Holders and their representatives the opportunity to conduct
a reasonable due diligence  inquiry of Company's  pertinent  financial and other
records and make  available its officers,  directors and employees for questions
regarding  such  information  as it  relates  to  information  contained  in the
registration statement.

        (l) Provide Holders and their  representatives the opportunity to review
the  registration  statement and all amendments  thereto a reasonable  period of
time prior to their  filing with the SEC and refrain from filing any document in
a form to which Holders reasonably object.

        7.  Furnish  Information.  It  shall  be a  condition  precedent  to the
obligations  of the Company to take any action  pursuant to this  Agreement with
regard to each selling  Holder that such selling  Holders  shall  furnish to the
Company such

                                       6



 


information regarding themselves,  the Registrable  Securities held by them, and
the intended  method of disposition  of such  securities as shall be required to
effect the  registration  of their  Registrable  Securities or to determine that
registration is not required pursuant to Rule 144 or other applicable  provision
of the Act.

        8. Expenses of Demand Registration. All expenses other than underwriting
discounts and commissions incurred in connection with registrations,  filings or
qualifications  pursuant to Sections 2 and 3, including (without limitation) all
registration, filing and qualification fees, printers' and accounting fees, fees
and disbursements of counsel for the Company,  and including the reasonable fees
and disbursements incurred of only one counsel for the selling Holders, shall be
borne  by  the  Company;  provided,  however,  that the  Company  shall  not  be
required to pay for any expenses of any  registration  proceeding begun pursuant
to  Section 3 if the  registration  request  is  subsequently  withdrawn  at the
request  of the  Holders  of a  majority  of the  Registrable  Securities  to be
registered (in which case all Holders who had requested such registration  shall
bear such  expenses);  provided  further,  however,  that if at the time of such
withdrawal,  the  Holders  have  learned  of a  material  adverse  change in the
condition,  business, or prospects of the Company from that known to the Holders
at the time of their request,  then the Holders shall not be required to pay any
of such expenses and shall retain their rights pursuant to Section 3.

        9. Expenses of Company Registration.  The Company shall bear and pay all
expenses incurred in connection with any  registration,  filing or qualification
of Registrable Securities with respect to the registration pursuant to Section 4
for each Holder,  including (without  limitation) all registration,  filing, and
qualification  fees,  printers and  accounting  fees  relating or  apportionable
thereto (and including the reasonable  fees and  disbursements  incurred of only
one  counsel  for  the  selling  Holders   selected  by  them),   but  excluding
underwriting discounts and commissions relating to Registrable Securities.

        10.  Indemnification.  In  the  event  any  Registrable  Securities  are
included in a registration statement under this Agreement:

        (a) To the extent  permitted by law, the Company will indemnify and hold
harmless each Holder, the officers and directors of each Holder, any underwriter
(as defined in the Act) for such Holder and each  person,  if any,  who controls
such  Holder or  underwriter  within the  meaning  of the Act or the  Securities
Exchange Act of 1934, as amended (the "1934 Act"),  against any losses,  claims,
damages,  or  liabilities  (joint or several)  to which they may become  subject
under the Act,  the 1934 Act or other  federal  or state  law,  insofar  as such
losses,  claims,  damages,  or liabilities (or actions in respect thereof) arise
out  of or  are  based  upon  any  of the  following  statements,  omissions  or
violations (collectively a "Violation"):  (i) any untrue statement of a material
fact  contained  in  such  registration  statement,  including  any  preliminary
prospectus  or  final  prospectus   contained   therein  or  any  amendments  or
supplements thereto, (ii) the omission to state therein a material fact required
to  be  stated  therein,  or  necessary  to  make  the  statements  therein  not
misleading,  or (iii) any violation by the Company of the Act, the 1934 Act, any

                                       7


 


state  securities law or any rule or regulation  promulgated  under the Act, the
1934 Act or any state  securities  law; and the Company will reimburse each such
Holder, officer or director,  underwriter or controlling person for any legal or
other expenses  reasonably  incurred by them in connection with investigating or
defending any such loss, claim, damage, liability, or action; provided, however,
that the indemnity  agreement contained in this subsection 10(a) shall not apply
to amounts paid in settlement of any such loss,  claim,  damage,  liability,  or
action if such settlement is effected  without the consent of the Company (which
consent shall not be unreasonably withheld),  nor shall the Company be liable in
any such case for any such  loss,  claim,  damage,  liability,  or action to the
extent  that it  arises  out of or is based  upon a  Violation  which  occurs in
reliance upon and in conformity with written information furnished expressly for
use in connection with such registration by any such Holder, officer,  director,
underwriter or controlling person.

        (b) To the extent  permitted by law, each selling Holder,  severally and
not  jointly,  will  indemnify  and  hold  harmless  the  Company,  each  of its
directors, each of its officers who have signed the registration statement, each
person,  if any,  who  controls  the Company  within the meaning of the Act, any
underwriter  and any  other  Holder  selling  securities  in  such  registration
statement or any of its  directors  or officers or any person who controls  such
Holder, against any losses,  claims,  damages, or liabilities (joint or several)
to which the  Company or any such  director,  officer,  controlling  person,  or
underwriter or controlling person, or other such Holder or director,  officer or
controlling  person may  become  subject,  under the Act,  the 1934 Act or other
federal or state law, insofar as such losses,  claims,  damages,  or liabilities
(or actions in respect thereto) arise out of or are based upon any Violation, in
each case to the extent (and only to the extent) that such  Violation  occurs in
reliance  upon and in  conformity  with  written  information  furnished by such
Holder  expressly for use in connection  with such  registration;  and each such
Holder will  reimburse any legal or other  expenses  reasonably  incurred by the
Company and any such  director,  officer,  controlling  person,  underwriter  or
controlling person, other Holder,  officer,  director,  or controlling person in
connection  with  investigating  or  defending  any such  loss,  claim,  damage,
liability, or action; provided,  however, that the indemnity agreement contained
in this  subsection  10(b) shall not apply to amounts paid in  settlement of any
such loss,  claim,  damage,  liability or action if such  settlement is effected
without the  consent of the  Holder,  which  consent  shall not be  unreasonably
withheld;  provided, that, in no event shall any indemnity under this subsection
10(b) exceed the gross proceeds from the offering received by such Holder.

        (c) Promptly after receipt by an indemnified party under this Section 10
of notice of the commencement of any action (including any governmental action),
such indemnified party will, if a claim in respect thereof is to be made against
any indemnifying  party under this Section 10, deliver to the indemnifying party
a written notice of the commencement  thereof and the  indemnifying  party shall
have the right to participate in, and, to the extent the  indemnifying  party so
desires,  jointly with any other indemnifying party similarly noticed, to assume
the defense thereof with counsel mutually satisfactory to the parties; provided,
however,  that an  indemnified  party  shall  have the right to  retain  its own
counsel,  with  the  reasonably  incurred  fees and  expenses  to be paid by the
indemnifying  party, if  representation of such indemnified party by the

                                       8



 


counsel retained by the indemnifying  party would be inappropriate due to actual
or potential  conflicting interests between such indemnified party and any other
party  represented  by such counsel in such  proceeding.  The failure to deliver
written  notice  to the  indemnifying  party  within  a  reasonable  time of the
commencement  of any such action,  if  prejudicial to its ability to defend such
action,   shall  relieve  such  indemnifying  party  of  any  liability  to  the
indemnified  party under this Section 10, but the omission so to deliver written
notice to the  indemnifying  party will not relieve it of any liability  that it
may have to any indemnified party otherwise than under this Section 10.

        (d)  In the event that the indemnity provided in  paragraph  (a)  or (b)
of this  Section  10 is  unavailable  to or  insufficient  to hold  harmless  an
indemnified  party for  any reason, the  Company and each  holder of Registrable
Securities agree  to contribute  to the  aggregate claims,  losses, damages  and
liabilities (including legal or other expenses reasonably incurred in connection
with  investigating  or defending  same)  (collectively 'Losses')  to  which the
Company and one or more of the holders of Registrable Securities may be  subject
in  such  proportion as  is appropriate  to  reflect the  relative fault  of the
Company and the  holders in connection  with the statements  or omissions  which
resulted  in such Losses; provided, however, that in no case shall any holder be
responsible for any  amount in excess  of the net  purchase price of  securities
sold  by it under the registration statement. Relative fault shall be determined
by reference to  whether any  alleged untrue  statement or  omission relates  to
information  provided by  the Company  or by  the holders.  The Company  and the
holders agree  that it  would not  be just  and equitable  if contribution  were
determined  by pro rata allocation or any  other method of allocation which does
not  take  account   of  the   equitable  considerations   referred  to   above.
Notwithstanding  the  provisions  of this  paragraph  (d), 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. For purposes  of this Section  10,
each  person who controls a holder  of Registrable Securities within the meaning
of either the  Securities Act or  the Exchange Act  and each director,  officer,
partner,  employee  and  agent  of  a  holder  shall  have  the  same  rights to
contribution as such holder, and each person who controls the Company within the
meaning of either the Securities  Act or the Exchange  Act and each director  of
the  Company, and each  officer of the  Company who has  signed the registration
statement, shall have the same rights to contribution as the Company, subject in
each case to the applicable terms and conditions of this paragraph (d).


        (e) The  obligations  of the Company and Holders  under this  Section 10
shall survive the redemption and conversion, if any, of the Preferred Stock, the
completion of any offering of Registrable Securities in a registration statement
under this Agreement, and otherwise.


        11. Reports Under Securities Exchange Act of 1934. With a view to making
available to the Holders the benefits of Rule 144 promulgated  under the Act and
any other rule or  regulation of the SEC that may at any time permit a Holder to
sell securities of the Company to the public without  registration,  the Company
agrees to:

        (a) make and keep  public  information  available,  as those  terms  are
understood and defined in SEC Rule 144;

        (b) file with the SEC in a timely manner all reports and other documents
required of the Company under the Act and the 1934 Act; and

        (c)  furnish to any Holder,  so long as the Holder owns any  Registrable
Securities,  forthwith upon request (i) a written  statement by the Company,  if
true, that it has complied with the reporting  requirements of SEC Rule 144, the
Act and the 1934 Act, (ii) a copy of the most recent annual or quarterly  report
of the Company and such other reports and documents so filed by the Company, and
(iii) such other  information  as may be  reasonably  requested  in availing any
Holder of any rule or  regulation  of the SEC which  permits  the selling of any
such securities without registration.

        12.  Amendment of Registration  Rights.  Any provision of this Agreement
may be amended and the observance  thereof may be waived (either generally or in
a particular instance and either retroactively or prospectively),  only with the
written  consent of the Company and the holders of a majority of the Registrable
Securities  provided that the amendment  treats all Holders equally and provided
further  that there can be no material  reduction in a Holder's  rights  without
consent of such Holder. Any amendment or waiver effected in accordance with this
paragraph  shall be  binding  upon each  Holder,  each  future  Holder,  and the
Company.

        13.  Notices.  All notices  required or permitted  under this  Agreement
shall be made in writing signed by the party making the same,  shall specify the
section  under  this  Agreement  pursuant  to which it is  given,  and  shall be
addressed if to (i) the Company at: President,  7 Powder Horn Drive,  Warren, NJ
07059,  Telephone No. (908) 271-

                                       9



 


1001,  Telecopy No. (908) 805-3931 and (ii) the Holders at their respective last
address as the party  shall  have  furnished  in writing as a new  address to be
entered on such  register.  Any  notice,  except as  otherwise  provided in this
Agreement,  shall  be made by fax and  shall  be  deemed  given  at the  time of
transmission of the fax.

        14. Termination. This Agreement shall terminate on the date that is five
years from the date of this Agreement; but without prejudice to (i) the parties'
rights and obligations  arising from breaches of this Agreement  occurring prior
to  such  termination,   (ii)  other  indemnification   obligations  under  this
Agreement,  or (iii) the Company's obligation to maintain the effectiveness of a
registration  statement filed prior thereto in accordance with the terms hereof,
and to fulfill its obligations hereunder  in  respect  thereof  until it  is  no
longer required to maintain the effectiveness thereof.

        15.  Assignment.  No  assignment,  transfer  or  delegation,  whether by
operation of law or otherwise, of any rights or obligations under this Agreement
by the  Company or any  Holder,  respectively,  shall be made  without the prior
written  consent of the  majority in  interest  of the  Holders or the  Company,
respectively;  provided  that the  rights of a Holder  may be  transferred  to a
subsequent  holder  of  the  Holder's  Registrable   Securities  (provided  such
transferee  shall  provide  to the  Company,  together  with  or  prior  to such
transferee's  request  to have  such  Registrable  Shares  included  in a Demand
Registration or Piggyback  Registration,  a writing  executed by such transferee
agreeing to be bound as a Holder by the terms of this  Agreement);  and provided
further  that the Company may  transfer  its rights and  obligations  under this
Agreement to a purchaser of all or a substantial  portion of its business if the
obligations of the Company under this  Agreement are assumed in connection  with
such  transfer,  either by merger or other  operation  of law (which may include
without  limitation a transaction  whereby the Registrable  Shares are converted
into securities of the successor in interest) or by specific assumption executed
by the transferee.

        16.  Governing Law. This Agreement shall be governed by and construed in
accordance  with  the  laws of the  State  of  Delaware,  U.S.A.  applicable  to
agreements made in and wholly to be performed in that  jurisdiction,  except for
matters  arising  under the Act or the  Securities  Exchange Act of 1934,  which
matters shall be construed and interpreted in accordance with such laws.

        IN WITNESS  WHEREOF,  the undersigned have executed this Agreement as of
the date first above written.

                                       CELGENE CORPORATION


                                       By: ________________________________
                                             _________________
                                             President


                                    Address:  ___________________

                                       10


 




                                              ___________________

                                              ___________________



                                       INVESTOR(S)


                                       ___________________________________
                                       Investor's Name


                                       By:_________________________________
                                               (Signature)


                                    Address:  ___________________

                                              ___________________

                                              ___________________





                                       11