EXHIBIT 10.24

                          REGISTRATION RIGHTS AGREEMENT

     REGISTRATION RIGHTS AGREEMENT, dated as of January 20, 1999, by and between
Celgene Corporation,  a Delaware  corporation (the "Company"),  and John Hancock
Mutual Life Insurance  Company,  John Hancock  Variable Life Insurance  Company,
Signature lA (Cayman) Ltd.,  Signature 3 Limited and Hancock Mezzanine  Partners
L.P. (collectively,  the "Purchasers" and singly, each "Purchaser") entered into
in  connection  with the  issuance  of a  Convertible  Note due January 20, 2004
convertible  into  shares of Common  Stock,  par value  $.01 per share  ("Common
Stock") of the Company.

     1. Certain Definitions.

     For purposes of this  Registration  Rights  Agreement,  the following terms
shall have the following respective meanings:

     (a) "Commission" shall mean the Securities and Exchange Commission,  or any
other  federal  agency  at  the  time  administering  the  Exchange  Act  or the
Securities Act, whichever is the relevant statute for the particular purpose.

     (b) Convertible Note" shall mean the Convertible Note due January 20, 2004,
of the Company to be issued and sold to the Purchaser,  and any Convertible Note
issued in exchange therefor or in lieu thereof.

     (c) "Effective  Time" shall mean the date on which the Commission  declares
the Shelf Registration  effective or on which the Shelf  Registration  otherwise
becomes effective.

     (d) "Exchange Act" shall mean the  Securities  Exchange Act of 1934, or any
successor thereto and the rules and regulations promulgated  thereunder,  as the
same shall be amended from time to time.

     (e)  "Issue  Date"  shall  mean  the date on  which a  Convertible  Note is
initially issued.

     (f) The term "person" shall mean a corporation,  association,  partnership,
organization,  business, individual, government or political subdivision thereof
or governmental agency.

     (g)  "Registration  Expenses"  shall have the meaning  assigned  thereto in
Section 4 hereof.

     (h)  "Securities  Act"  shall  mean  the  Securities  Act of  1933,  or any
successor thereto and the rules and regulations promulgated  thereunder,  as the
same shall be amended from time to time.




     (i) "Shares" means the shares of Common Stock issuable upon exercise of the
Convertible Note.

     (j) "Shelf Registration" shall have the meaning assigned thereto in Section
2 hereof.

     In addition,  capitalized  terms not defined  herein shall have the meaning
ascribed in the Convertible Note.

     2. Shelf Registration of Shares.

     (a) Not later than  January  20,  2000,  the  Company  shall file under the
Securities Act a "shelf"  registration  statement providing for the registration
of, and the sale on a  continuous  or delayed  basis by the  Purchasers  of, all
shares issuable upon conversion of the Convertible  Notes,  pursuant to Rule 415
under the  Securities  Act  and/or any  similar  rule that may be adopted by the
Commission  (the  "Shelf  Registration").  The  Company  agrees  to use its best
efforts to cause the Shelf  Registration  to become or be declared  effective no
later than 45  calendar  days after the  filing  thereof  and to keep such Shelf
Registration continuously effective for a period ending on the earliest to occur
of (i) the  second  anniversary  of the Issue  Date,  (ii)  notification  to the
Company by each Purchaser that it has sold all Shares  issuable upon  conversion
of the  Convertible  Notes so owned by it, or (iii) such time as the  Purchasers
may sell all of such shares  pursuant to Rule 144(k) under the  Securities  Act.
The Company  further agrees,  if necessary,  to supplement or make amendments to
the Shelf  Registration,  if required by the rules,  regulations or instructions
applicable  to  the  registration  form  used  by the  Company  for  such  Shelf
Registration  or by the Securities Act or rules and  regulations  thereunder for
shelf  registration,  and the Company agrees to furnish to each Purchaser copies
of any such  supplement  or amendment  prior to its being used and/or filed with
the Commission,  and will not file any such supplement or amendment to which any
Purchaser reasonably objects.

     (b) Notwithstanding the foregoing, following the effectiveness of the Shelf
Registration,  the Company many, at any time,  suspend the effectiveness of such
Shelf Registration for up to 60 days, as appropriate (a "Suspension Period"), by
giving notice to each  Purchaser,  if the Company shall have determined that the
Company may be required to disclose any  material  corporate  development  which
disclosure  may  jeopardize a material  transaction or otherwise have a material
adverse effect on the Company. The Company will use its best efforts to minimize
the length of any Suspension Period. Notwithstanding the foregoing, no more than
one  Suspension  Period may occur within any 180 day period,  and no  Suspension
Period  shall be  effective  at any time the  Company  or any  affiliate  of the
Company is publicly  selling  shares of the capital stock of the Company  (other
than  pursuant  to a  registration  statement  on the  Securities  and  Exchange
Commission  Form  S-8).  The  period  of any  such  suspension  of  registration
statement  shall be added to the period of time the  Company  agrees to keep the
Shelf Registration  effective as provided in Section 2(a). Each Purchaser agrees
that, upon receipt of any notice from the Company of a Suspension  Period,  such
Purchaser shall forthwith discontinue disposition of shares covered by the Shelf
Registration  until such Purchaser (i) is advised in writing by the Company that
the use of the



                                       2




applicable prospectus may be resumed, (ii) has received copies of a supplemental
or amended  prospectus,  if  applicable,  and (iii) has  received  copies of any
additional  or  supplemental  filings  which are  incorporation  or deemed to be
incorporated by reference in such prospectus.

     3. Registration Procedures.

     (a) In connection  with any  obligation of the Company to register  Shares,
the Company shall use its best efforts to effect or cause such  registration  to
permit the sale of the Shares by the Purchasers in accordance  with the intended
method  or  methods  of  distribution   thereof   described  in  the  applicable
registration statement.  In connection therewith,  the Company shall, within the
time specified in Section 2 above:

     (i) prepare and file with the  Commission a  registration  statement on any
form which may be utilized by the Company and which shall permit the disposition
of the Shares in  accordance  with the intended  method or methods  thereof,  as
specified in writing by each Purchaser;

     (ii) comply with the  provisions of the  Securities Act with respect to the
disposition  of all of the Shares  covered  by such  registration  statement  in
accordance with the intended  methods of disposition by each Purchaser set forth
in such registration statements;

     (iii) provide (A) each  Purchaser,  (B) the  underwriters  (which term, for
purposes of these  Registration  Rights,  shall include a person deemed to be an
underwriter  within the meaning of Section 2(11) of the Securities Act), if any,
thereof,  (C) the sales or placement  agent, if any,  therefor,  (D) counsel for
such  underwriters or agent,  and (E) counsel for the Purchasers the opportunity
to  participate  in  the  preparation  of  such  registration  statement,   each
prospectus included therein or filed with the Commission,  and each amendment or
supplement thereto;

     (iv) for a  reasonable  period  prior to the  filing  of such  registration
statement,  and  throughout  the  period  specified  in  Section 2 hereof,  make
available for inspection by the parties  referred to in Section  3(a)(iii) above
who shall certify to the Company that they have a current  intention to sell the
Shares  pursuant  to  the  registration   statement  such  financial  and  other
information  and books  and  records  of the  Company,  and cause the  officers,
employees,  counsel and independent  certified public accountants of the Company
to respond to such inquiries,  as shall be reasonably necessary, in the judgment
of the respective  counsel referred to in such Section,  to conduct a reasonable
investigation  within the meaning of Section 11 of the Securities Act; provided,
however,  that each such party shall be required to maintain in  confidence  and
not to disclose to any other person any  information or records  provided by the
Company and clearly marked or otherwise adequately  identified by the Company as
being confidential  until such time as (A) such information  becomes a matter of
public record (whether by virtue of its inclusion in



                                       3



such registration statement or otherwise),  or (B) such person shall be required
so to disclose such  information  pursuant to the subpoena or order of any court
or other governmental agency or body having jurisdiction over the matter or over
such party  (subject  to the  requirements  of such  order,  and only after such
person  shall  have  given  the  Company  prompt  prior  written  notice of such
requirement),  or (C)  such  information  is  required  to be set  forth in such
registration  statement or the prospectus included therein or in an amendment to
such registration  statement or an amendment or supplement to such prospectus in
order that such registration statement,  prospectus, amendment or supplement, as
the case may be, does not contain an untrue statement of a material fact or omit
to state therein a material  fact required to be stated  therein or necessary to
make the statements therein not misleading;

     (v) promptly notify each Purchaser,  the sales or placement  agent, if any,
therefor and the  managing  underwriter  or  underwriters,  if any,  thereof and
confirm  such advice in writing,  (A) when such  registration  statement  or the
prospectus  included  therein  or any  prospectus  amendment  or  supplement  or
post-effective  amendment has been filed, and, with respect to such registration
statement or any post-effective  amendment,  when the same has become effective,
(B) of any  comments  by the  Commission  and  by  the  Blue  Sky or  securities
commissioner  or regulator  of any state with respect  thereto or any request by
the Commission for amendments or supplements to such  registration  statement or
prospectus or for additional information,  (C) of the issuance by the Commission
of any stop order suspending the effectiveness of such registration statement or
the initiation or overt threatening of any proceedings for that purpose,  (D) if
at any time the  representations  and warranties of the Company  contemplated by
Section 5 hereof cease to be true and correct in all material  respects,  (E) of
the receipt by the Company of any notification with respect to the suspension of
the  qualification  of the Shares for sale in any jurisdiction or the initiation
or overt threatening of any proceeding for such purpose, or (F) at any time when
a  prospectus  is required to be  delivered  under the  Securities  Act, if such
registration  statement,  prospectus,  prospectus  amendment  or  supplement  or
post-effective  amendment,  or any document  incorporated by reference in any of
the foregoing, contains 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 light of the circumstances then existing;

     (vi) use its best efforts to obtain the withdrawal of any order  suspending
the effectiveness of such registration statement or any post-effective amendment
thereto at the earliest practicable date;

     (vii)  if  requested  by any  managing  underwriter  or  underwriters,  any
placement or sales agent or any Purchaser,  promptly incorporate in a prospectus
supplement or  post-effective  amendment such  information as is required by the
applicable   rules  and   regulations  of  the  Commission  that  such  managing
underwriter  or  underwriters,  such agent or such  Purchaser  specify should be
included therein


                                       4



relating to the terms of the sale of such Shares, including, without limitation,
information with respect to the number of Shares being sold by such Purchaser or
agent or to any underwriters,  the name and description of such Purchaser, agent
or underwriter,  the offering price of such Shares and any discount,  commission
or other compensation  payable in respect thereof, the purchase price being paid
therefor  by such  underwriters  and  with  respect  to any  other  terms of the
offering  of the  Shares  to be sold  by  such  Purchaser  or  agent  or to such
underwriters;  and make all required  filings of such  prospectus  supplement or
post-effective  amendment  promptly  after  notification  of the  matters  to be
incorporated in such prospectus supplement or post-effective amendment;

     (viii) furnish to each  Purchaser,  each placement or sales agent,  if any,
therefor, each underwriter,  if any, thereof and the respective counsel referred
to in Section  3(a)(iii) a copy of such  registration  statement  in the form in
which it became effective,  each such amendment and supplement  thereto (in each
case  including  all exhibits  thereto and documents  incorporated  by reference
therein)  and such number of copies of such  registration  statement  (excluding
exhibits  thereto  and  documents   incorporated  by  reference  therein  unless
specifically so requested by any Purchaser,  agent or  underwriter,  as the case
may be) and of the prospectus included in such registration statement (including
each preliminary prospectus and any summary prospectus),  in conformity with the
requirements of the Securities Act, and such other documents,  as any Purchaser,
agent,  if any,  and  underwriter,  if any, may  reasonably  request in order to
facilitate the offering and  disposition of the Shares owned by such  Purchaser,
offered or sold by such agent or underwritten by such  underwriter and to permit
such  Purchaser,  agent and  underwriter  to  satisfy  the  prospectus  delivery
requirements  of the Securities  Act; and the Company hereby consents to the use
of such prospectus  (including such preliminary and summary  prospectus) and any
amendment  or  supplement  thereto  by any  Purchaser  and by any such agent and
underwriter,  in each case in the form most  recently  provided to such party by
the Company,  in connection  with the offering and sale of the Shares covered by
the  prospectus  (including  such  preliminary  and summary  prospectus)  or any
supplement or amendment thereto;

     (ix) use its best  efforts  to (A)  register  or  qualify  the Shares to be
included in such  registration  statement under such securities laws or blue sky
laws of such  jurisdictions as each Purchaser and each placement or sales agent,
if any, therefor and underwriter,  if any, thereof shall reasonably request, (B)
keep such registrations or qualifications in effect and comply with such laws so
as to permit the  continuance  of  offers,  sales and  dealings  therein in such
jurisdictions  during the respective  periods such  registration  statements are
required  to remain  effective  under  Section 2 above and for so long as may be
necessary to enable each  Purchaser or any agent or  underwriter to complete its
distribution of Shares pursuant to such registration  statement and (C) take any
and all other actions as may be reasonably necessary or advisable to enable each
Purchaser, agent, if any, and underwriter, if any, to


                                       5



consummate  the  disposition  in such  jurisdictions  of such Shares;  provided,
however,  that the  Company  shall not be required  for any such  purpose to (I)
qualify  as a  foreign  corporation  in any  jurisdiction  wherein  it would not
otherwise  be  required  to qualify  but for the  requirements  of this  Section
3(a)(ix) or (II) consent to general service of process in any such jurisdiction;

     (x) use its  best  efforts  to  obtain  the  consent  or  approval  of each
governmental agency or authority,  whether federal, state or local, which may be
required to effect the Shelf  Registration or the offering or sale in connection
therewith or to enable the Purchaser to offer,  or to consummate the disposition
of, its Shares;

     (xi) cooperate with each Purchaser and the managing  underwriters,  if any,
to  facilitate  the  timely   preparation  and  delivery  of  any   certificates
representing   Shares  to  be  sold,  which   certificates   shall  be  printed,
lithographed or engraved,  or produced by any  combination of such methods,  and
which shall not, once sold under the Shelf  Registration,  bear any  restrictive
legends; and, in the case of an underwritten offering,  enable such Shares to be
in such denominations and registered in such names as the managing  underwriters
may request at least two business days prior to any sale of the Shares;

     (xii) enter into one or more underwriting  agreements,  engagement letters,
agency  agreements or similar  agreements,  as appropriate,  including  (without
limitation)  customary  provisions relating to indemnification and contribution,
and take such other  actions in  connections  therewith as any  Purchaser  shall
reasonably  request in order to expedite or facilitate  the  disposition  of the
Shares;

     (xiii)  notify each  Purchaser in writing of any proposal by the Company to
amend or waive any provision of these  Registration  Rights  pursuant to Section
7(g) hereof and of any amendment or waiver effected  pursuant  thereto,  each of
which  notices  shall  contain the text of the  amendment or waiver  proposed or
effected, as the case may be;

     (xiv) in the event that any broker-dealer registered under the Exchange Act
shall  underwrite  any  Shares or  participate  as a member  of an  underwriting
syndicate or selling group or "assist in the  distribution"  (within the meaning
of the Rules of Fair  Practice  and the By-Laws of the National  Association  of
Securities  Dealers,  Inc.  ("NASD"))  thereof,  whether  as an  underwriter,  a
placement or sales agent or a broker or dealer in respect thereof, or otherwise,
assist such  broker-dealer  in complying with the requirements of such Rules and
By-Laws,  including,  without limitation,  by providing such information to such
broker-dealer as may be required in order for such  broker-dealer to comply with
the requirements of the Rules of Fair Practice of the NASD;


                                       6




     (xv) comply with all applicable  rules and  regulations of the  Commission,
and make generally  available to its security holders as soon as practicable but
in any event not later than  eighteen  months after the  effective  date of such
registration  statement, an earning statement of the Company and in subsidiaries
complying with Section 11 (a) of the Securities Act (including, at the option of
the Company, Rule 158 thereunder); and

     (xvi) use its best  efforts to have the Shares  approved for trading on the
Nasdaq National Market.

     (b) In the event that the Company  would be  required,  pursuant to Section
3(a)(v)(F)  above,  to notify each  Purchaser,  the placement or sales agent, if
any, therefor and the managing underwriters,  if any, thereof, the Company shall
without delay prepare and furnish to each Purchaser,  to each placement or sales
agent, if any, and to each underwriter, if any, a reasonable number of copies of
a  prospectus   supplemented  or  amended  in  form  and  substance   reasonably
satisfactory to them, so that, as thereafter  delivered to purchasers of Shares,
such prospectus shall not contain 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 light of the circumstances  then existing.
Each Purchaser  agrees that upon receipt of any notice from the Company pursuant
to Section  3(a)(v)(F)  hereof,  such Purchaser shall forthwith  discontinue the
disposition of Shares pursuant to the registration  statement applicable to such
Shares  until such  Purchaser  shall  have  received  copies of such  amended or
supplemented prospectus, and if so directed by the Company, such Purchaser shall
deliver  to the  Company  (at the  Company's  expense)  all  copies,  other than
permanent  file copies,  then in such  Purchaser's  possession of the prospectus
covering such Shares at the time of receipt of such notice.

     (c) The Company may require any  Purchaser  to furnish to the Company  such
information  regarding such Purchaser and such  Purchaser's  intended  method of
distribution  of the  Shares as the  Company  may from  time to time  reasonably
request in writing,  but only to the extent that such information is required in
order to comply with the  Securities  Act. Each  Purchaser  agrees to notify the
Company as promptly as  practicable  of any  inaccuracy or change in information
previously  furnished by such  Purchaser to the Company or of the  occurrence of
any event in either  case as a result of which any  prospectus  relating to such
registration  contains or would  contain an untrue  statement of a material fact
regarding such Purchaser or such Purchaser's  intended method of distribution of
such Shares or omits to state any material fact regarding such Purchaser or such
Purchaser's intended method of distribution of such Shares required to be stated
therein or necessary to make the  statements  therein not misleading in light of
the  circumstances  then  existing,  and  promptly to furnish to the Company any
additional  information  required to correct and update any previously furnished
information or required so that such prospectus shall not contain,  with respect
to such Purchaser or the  distribution of such Shares,  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  light  of the
circumstances  then  existing.  Each Purchaser  agrees that upon  delivering any
notice to the Company  pursuant  to this  Section  3(c),  such  Purchaser  shall
forthwith  discontinue the  disposition of Shares  pursuant to the  registration
statement applicable to such Shares until such


                                       7



Purchaser shall have received copies of such amended or supplemented prospectus,
and if so directed by the Company,  such Purchaser  shall deliver to the Company
(at the Company's expense) all copies,  other than permanent file copies then in
such Purchaser's  possession of the prospectus  covering such Shares at the time
of receipt of such notice.

     4. Registration Expenses.

     The  Company  agrees to bear and to pay or cause to be paid  promptly  upon
request being made therefor all expenses  incident to the Company's  performance
of or  compliance  with these  Registration  Rights as they  relate to the Shelf
Registration,  including,  without  limitation,  (i) all Commission and any NASD
registration  and  filing  fees and  expenses,  (ii) all  fees and  expenses  in
connection with the  qualification of the Shares for offering and sale under the
State  securities  and blue sky laws  referred  to in Section  3(a)(ix)  hereof,
including  reasonable  fees and  disbursements  of counsel for the  placement or
sales agent or underwriters in connection  with such  qualifications,  (iii) all
fees and expenses in  connection  with the approval for trading of the Shares on
the Nasdaq  National  Market,  (iv) all  expenses  relating to the  preparation,
printing,  distribution and reproduction of each registration statement required
to be  filed  hereunder,  each  prospectus  included  therein  or  prepared  for
distribution pursuant hereto, each amendment or supplement to the foregoing, the
certificates  representing  the Shares and all other documents  relating hereto,
(v) internal expenses (including,  without limitation, all salaries and expenses
of the Company's officers and employees  performing legal or accounting duties),
and (vi) fees,  disbursements and expenses of counsel and independent  certified
public  accountants  of the Company  (including  the expenses of any opinions or
"cold  comfort"  letters  required  by  or  incident  to  such  performance  and
compliance)  (collectively,  the "Registration  Expenses").  Notwithstanding the
foregoing,  such  Purchaser  shall  pay all  agency  fees  and  commissions  and
underwriting  discounts and  commissions  attributable to the sale of the Shares
and the fees and  disbursements  of any  counsel  or other  advisors  or experts
retained by such Purchaser in connection with the sale of its shares.

     5. Representations and Warranties.

     The Company represents and warrants to, and agrees with, each
Purchaser that:

     (a)  Each  registration  statement  covering  Shares  and  each  prospectus
(including any preliminary or summary prospectus) contained therein or furnished
pursuant to Section  3(a)(viii) hereof and any further amendments or supplements
to any such registration  statement or prospectus,  when it becomes effective or
is  filed  with the  Commission,  as the  case  may be,  and,  in the case of an
underwritten  offering  of  Shares,  at  the  time  of  the  closing  under  the
underwriting agreement relating thereto will conform in all material respects to
the requirements of the Securities Act, and will not contain 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;  and at all
times subsequent to the Effective Time when a prospectus would be required to be
delivered  under the  Securities  Act, other than from (i) such time as a notice
has been give to such Purchaser  pursuant to Section 3(a)(v)F) hereof until (ii)
such  time as the  Company  furnishes  an  amended  or  supplemented  prospectus
pursuant to Section  3(b) hereof,  each such  registration  statement,  and each
prospectus


                                       8



(including any summary  prospectus)  contained therein or furnished  pursuant to
Section 3(a)(viii) hereof, as then amended or supplemented,  will conform in all
material  respects  to the  requirements  of the  Securities  Act,  and will not
contain 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 then existing;  provided,  however,
that this  representation  and  warranty  shall not apply to any  statements  or
omissions made in reliance upon and in conformity with information  furnished in
writing to the Company by such Purchaser expressly for use therein.

     (b) Any documents  incorporated by reference in any prospectus  referred to
in Section  5(a)  hereof,  when they become or became  effective  or are or were
filed with the Commission, or if amended, when amended, as the case may be, will
conform  or  conformed  in all  material  respects  to the  requirements  of the
Exchange  Act,  and none of such  documents  will contain or contained an untrue
statement  of a material  fact or will omit or omitted to state a material  fact
required to be stated  therein or necessary to make the  statements  therein not
misleading;  provided,  however, that this representation and warranty shall not
apply to any  statements  or omissions  made in reliance  upon and in conformity
with information furnished in writing to the Company by such Purchaser expressly
for use therein.

     6. Indemnification.


     (a)  Indemnification  by the  Company.  Upon  the  registration  of  Shares
pursuant to Section 2 hereof,  and in  consideration  of the  agreements  of the
Purchasers  contained herein, and as an inducement to the Purchasers to purchase
the Convertible Notes, the Company shall, and it hereby agrees to, indemnify and
hold harmless each Purchaser and each person who  participates as a placement or
sales agent or as an  underwriter in any offering or sale of such Shares against
any losses,  claims,  damages or  liabilities,  joint or several,  to which such
Purchaser  or any  such  agent or  underwriter  may  become  subject  under  the
Securities  Act or  otherwise,  insofar  as  such  losses,  claims,  damages  or
liabilities  (or actions in respect  thereof)  arise out of or are based upon an
untrue statement or alleged untrue statement of a material fact contained in any
registration  statement  under  which  such  Shares  were  registered  under the
Securities  Act,  or any  preliminary,  final or  summary  prospectus  contained
therein or furnished by the Company to such Purchaser, agent or underwriter,  or
any  amendment  or  supplement  thereto,  or arise out of or are based  upon the
omission or alleged  omission to state  therein a material  fact  required to be
stated therein or necessary to make the statements  therein not misleading,  and
the Company shall, and it hereby agrees to, reimburse such Purchaser, such agent
and such underwriter for any legal or other expenses reasonably incurred by them
in connection with  investigating  or defending any such action or claim as such
expenses are incurred;  provided,  however, that the Company shall not be liable
to any such  Person in any such case to the extent  that any such  loss,  claim,
damage  or  liability  arises  out of or is based  upon an untrue  statement  or
alleged  untrue   statement  or  omission  or  alleged  omission  made  in  such
registration statement or preliminary, final or summary prospectus, or amendment
or  supplement  in reliance  upon and in  conformity  with  written  information
furnished  to the Company by such Person  expressly  for use  therein;  provided
further,  however,  that the  Company  shall not be liable to any such Person if
such Person failed to deliver a prospectus in the form most recently provided by
the Company (including any amendments or supplements thereto previously provided
by the


                                       9




Company),  in any such  case to the  extent  that any  loss,  claim,  damage  or
liability  arises out of or is based  upon an untrue  statement  or an  omission
which was corrected in such most recently  furnished  prospectus  (including any
such amendments or supplements).

     (b)  Indemnification by the Purchaser and any Agents and Underwriters.  The
Company may require,  as a condition to including any Shares in any registration
statement   filed  pursuant  to  Section  2  hereof  and  to  entering  into  an
underwriting  agreement,  if any, with respect  thereto,  that the Company shall
have  received  an  undertaking   reasonably   satisfactory   to  it  from  each
participating  Purchaser and from each  underwriter,  if any,  named in any such
underwriting  agreement,  severally and not jointly or jointly and severally, to
(i) indemnify and hold harmless the Company against any losses,  claims, damages
or liabilities to which the Company may become subject, under the Securities Act
or otherwise, insofar as such losses, claims, damages or liabilities (or actions
in  respect  thereof')  arise out of or are based  upon an untrue  statement  or
alleged  untrue  statement of a material  fact  contained  in such  registration
statement, or any preliminary,  final or summary prospectus contained therein or
furnished  by the  Company  to  any  Purchaser,  agent  or  underwriter,  or any
amendment or supplement  thereto, or arise out of or are based upon the omission
or alleged  omission  to state  therein a material  fact  required  to be stated
therein or necessary to make the statements therein not misleading, in each case
to the extent,  but only to the extent,  that such untrue  statement  or alleged
untrue  statement or omission or alleged  omission was made in reliance upon and
in  conformity  with  written  information  furnished  to the  Company  by  such
Purchaser or  underwriter  expressly  for use therein,  and (ii)  reimburse  the
Company for any legal or other  expenses  reasonably  incurred by the Company in
connection  with  investigating  or  defending  any such action or claim as such
expenses  are  incurred.  Notwithstanding  the  above,  the  obligation  of such
Purchaser for indemnity  shall be limited to an amount equal to the net proceeds
received by such Purchaser in the applicable underwriting.

     (c) Notices of Claims,  Etc. Promptly after receipt by an indemnified party
under  subsection (a) or (b) above of written notice of the  commencement of any
action,  such  indemnified  party shall,  if a claim in respect thereof is to be
made against an indemnifying party pursuant to the indemnification provisions of
or contemplated by this Section 6, notify such indemnifying  party in writing of
the commencement of such action;  but the omission so to notify the indemnifying
party  shall  not  relieve  it  from  any  liability  which  it may  have to any
indemnified  party  other  than  under  the  indemnification  provisions  of  or
contemplated  by Section 6(a) or 6(b)  hereof.  In case any such action shall be
brought against any indemnified party and it shall notify an indemnifying  party
of the  commencement  thereof,  such  indemnifying  party  shall be  entitled to
participate  therein  and, to the extent that it shall  wish,  jointly  with any
other indemnifying party similarly notified, to assume the defense thereof, with
counsel  satisfactory to such indemnified  party (who shall not, except with the
consent of the indemnified  party, be counsel to the indemnifying  party),  and,
after  notice  from  the  indemnifying  party to such  indemnified  party of its
election so to assume the defense thereof,  such indemnifying party shall not be
liable to such indemnified  party for any legal expenses of other counsel or any
other expenses, in each case subsequently incurred by such indemnified party, in
connection with the defense thereof other than reasonable costs of investigation
unless, in the case of an indemnification  obligation arising under Section (a),
(i) the employment of such additional  counsel has been authorized in writing by
the Company in connection with defending such action,


                                       10



or (ii) the Company and the  Purchaser  are advised by such  additional  counsel
that the Purchaser has available  defenses  involving a potential  conflict with
the  interests  of the Company,  in which  event,  the fees and expenses of such
additional  counsel shall be borne by the Company.  No indemnifying  party shall
consent to entry of any judgment or enter into any settlement of a claim against
an indemnified party without the consent of the indemnified party which does not
include as an unconditional term thereof the giving by the claimant or plaintiff
to such  indemnified  party of an  unconditional  release from all  liability in
respect to such claim or litigation.

     (d)  Contribution.  Each party hereto  agrees  that,  if for any reason the
indemnification  provisions  contemplated  by Section  6(a) or Section  6(b) are
unavailable to or insufficient to hold harmless an indemnified  party in respect
of any losses,  claims,  damages or liabilities (or actions in respect  thereof)
referred to therein, then each indemnifying party shall contribute to the amount
paid or payable by such  indemnified  party as a result of such losses,  claims,
damages or liabilities (or actions in respect  thereof) in such proportion as is
appropriate to reflect the relative  benefits  received by indemnified  party on
the one hand and the  indemnifying  party on the other from any  offering of the
Shares.  If,  however,  the  allocation  provided by the  immediately  preceding
sentence is not permitted by applicable law or if the  indemnified  party failed
to give the notice required under subsection (c) above,  then each  indemnifying
party shall contribute to such amount paid or payable by such indemnified  party
in such proportion as is appropriate to reflect not only such relative  benefits
but also the relative fault of the indemnifying  party and the indemnified party
in connection  with the  statements or omissions  which resulted in such losses,
claims,  damages or liabilities (or actions in respect thereof),  as well as any
other relevant equitable  considerations.  The relative benefits received by the
Company on the one hand and each Purchaser on the other shall be deemed to be in
the same  proportion as the total  purchase  price  received by the Company upon
issuance of the  Convertible  Note bears to the difference  between the proceeds
from the offering of the Shares  received by such  Purchaser  and such  purchase
price. The relative fault of such indemnifying party and indemnified party shall
be determined by reference to, among other things, whether the untrue or alleged
untrue  statement of a material fact or omission or alleged  omission to state a
material fact relates to information  supplied by such indemnifying  party or by
such indemnified party, and the parties' relative intent,  knowledge,  access to
information  and  opportunity  to correct or prevent such statement or omission.
The  parties   hereto  agree  that  it  would  not  be  just  and  equitable  if
contributions  pursuant  to  this  Section  6(d)  were  determined  by pro  rata
allocation  (even if any Purchaser or any agents or  underwriters or all of them
were  treated  as one  entity  for  such  purpose)  or by any  other  method  of
allocation which does not take account of the equitable  considerations referred
to in this Section 6(d). The amount paid or payable by an indemnified party as a
result of the losses,  claims,  damages,  or liabilities  (or actions in respect
thereof) referred to above shall be deemed to include any legal or other fees or
expenses  reasonably  incurred  by such  indemnified  party in  connection  with
investigating  or  defending  any such  action  or  claim.  Notwithstanding  the
provisions of this Section  6(d),  no Purchaser  shall be required to contribute
any amounts in excess of the amount by which the dollar  amount of the  proceeds
received by such  Purchaser  from the sale of any Shares  (after  deducting  any
fees,  discounts and commissions  applicable  thereto) exceeds the amount of any
damages which such  Purchaser  has  otherwise  been required to pay by reason of
such untrue or alleged untrue statement or omission or alleged omission,  and no
underwriter  shall be required to contribute  any amount in excess of the amount
by


                                       11




which the total price at which the Shares  underwritten by it and distributed to
the public were  offered to the public  exceeds the amount of any damages  which
such  underwriter has otherwise been required to pay by reason of such untrue or
alleged untrue  statement or omission or alleged  omission.  No person guilty of
fraudulent  misrepresentation  (within  the  meaning  of  Section  11 (f) of the
Securities  Act) shall be  entitled  to  contribute  from any person who was not
guilty of such fraudulent  misrepresentation.  Any underwriters'  obligations in
this Section 6(d) to contribute  shall be several in proportion to the principal
amount of Shares underwritten by them and not joint.

     (e) The  obligations  of the  Company  under  this  Section  6 shall  be in
addition to any liability which the Company may otherwise have and shall extend,
upon the same terms and  conditions,  to each  officer,  director and partner of
each  Purchaser,  any agent and any  underwriter  and each  person,  if any, who
controls such  Purchaser or any agent or  underwriter  within the meaning of the
Securities  Act;  and the  obligations  of each  Purchaser  and any  agents  and
underwriters  contemplated  by  this  Section  6  shall  be in  addition  to any
liability which such Purchaser or any such agent or  underwriter,  respectively,
may otherwise have and shall extend, upon the same terms and conditions, to each
officer and director of the Company (including any person who, with his consent,
is named in any  registration  statement  as about to become a  director  of the
Company) and to each person, if any, who controls the Company within the meaning
of the Securities Act.

     7. Miscellaneous

     (a) No Inconsistent Agreements. The Company represents, warrants, covenants
and agrees that it has not  granted,  and shall not grant,  registration  rights
with respect to Shares or any other  securities  which would  conflict  with the
terms contained in these Registration Rights.


     (b) Specific Performance.  The parties hereto acknowledge that there may be
no adequate  remedy at law if any party fails to perform any of its  obligations
hereunder and that each party may be irreparably harmed by any such failure, and
accordingly  agree that each party,  in addition to any other remedy to which it
may be  entitled  at law or in  equity,  shall be  entitled  to compel  specific
performance of the obligations of any other party under the Registration  Rights
in accordance with the terms and conditions of these Registration Rights, in any
court of the United States or any State thereof having jurisdiction.

     (c) Notices. Any notice or other communication  required or permitted to be
given hereunder  shall be deemed  effectively  given when personally  delivered,
telexed,  transmitted by facsimile or mailed by pre-paid  certified mail, return
receipt  requested,  or by  telephone  when  confirmed  in writing by one of the
preceding methods addressed as follows (as applicable):

     If to the Company, to:


     Celgene Corporation
     7 Powder Horn Drive
     Warren, NJ 07059


                                       12




     Attention:  John W. Jackson
     Telephone  Number:  (732)  271-1001
     Facsimile Transmission Number: (732) 805-3931

     with a copy to:

     Proskauer Rose LLP
     1585 Broadway
     New York, NY 10036

     Attention: Robert A. Cantone, Esq.
     Telephone Number: (212) 969-3000
     Facsimile Transmission Number: (212) 969-2900

     If to Purchasers,  to the Person designated by Purchaser and at the address
     as set forth on Schedule I in the Note  Purchase  Agreement  dated the date
     hereof between the Purchasers and the Company

     with a copy to:

     Choate, Hall & Stewart
     Exchange Place
     53 State Street
     Boston, MA 02109

     Attention: Frank B. Porter, Jr.
     Telephone Number: (617) 248-5000
     Facsimile Transmission Number: (617) 248-4000

or to such other  address or number and to the attention of such other person as
either party may designate by written notice to the other party. Notice shall be
effective upon actual receipt.

     (d) Survival.  The  respective  indemnities,  agreements,  representations,
warranties and each other  provision set forth in these  Registration  Rights or
made  pursuant  hereto shall remain in full force and effect  regardless  of any
investigation  (or statement as to the results  thereof) made by or on behalf of
each Purchaser, any director, officer or partner of such Purchaser, any agent or
underwriter  or any director,  officer or partner  thereof,  or any  controlling
person of any of the  foregoing  and shall survive the transfer of the Shares by
such Purchaser.

     (e) Law  Governing.  These  Registration  Rights  shall be  governed by and
construed in accordance with the laws of the State of New York.

     (f)  Headings.  The  descriptive  headings  of  the  several  Sections  and
paragraphs of these  Registration  Rights are inserted for convenience  only, do
not constitute a part of these



                                       13



Registration   Rights  and  shall  not   affect  in  any  way  the   meaning  or
interpretation of these Registration Rights.

     (g) Entire Agreement;  Amendments.  These Registration Rights and the other
writings  referred  to herein or  delivered  pursuant  hereto  which form a part
hereof  contain  the entire  understanding  of the parties  with  respect to its
subject matter.  These  Registration  Rights  supersede all prior agreements and
understandings  between the parties  with respect to its subject  matter.  These
Registration  Rights  may be  amended  and the  observance  of any term of these
Registration  Rights may be waived (either generally or in a particular instance
and either  retroactively or  prospectively)  only be a written  instrument duly
executed by the Company and each Purchaser.


     (h)  Assignment.   In  connection  with  any  permitted   transfer  of  the
Convertible  Note or any portion thereof in a principal  amount of not less than
$100,000  any  Purchaser  may  assign its  rights  hereunder  in respect of such
Convertible Note to the transferee.  Upon such assignment the transferee  shall,
insofar as the transferred  Convertible Notes are concerned,  be entitled to all
of the rights,  and be subject to all of the  obligations,  of a Purchaser under
these  Registration  Rights, and all references to such "Purchaser" herein shall
thereafter be deemed to refer to the Purchaser, or such transferee,  or both, as
the circumstances warrant.

     (i)   Counterparts.   This   agreement  may  be  executed  by  the  parties
counterparts,  each of which  shall be  deemed to be an  original,  but all such
respective counterparts shall together constitute one and the same instrument.

     [the remainder of this page is intentionally left blank]




                                       14



                 Signature Page of Registration Rights Agreement

            Agreed to and accepted as of the date referred to above,

CELGENE CORPORATION

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title:
           --------------------------------

     JOHN HANCOCK MUTUAL LIFE INSURANCE COMPANY

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title:
           --------------------------------

     JOHN HANCOCK VARIABLE LIFE INSURANCE COMPANY

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title:
           --------------------------------

     SIGNATURE 1 A (CAYMAN), LTD.
     By: John Hancock Mutual Life Insurance
              Company, Portfolio Advisor

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title:
           --------------------------------




                 Signature Page of Registration Rights Agreement

            Agreed to and accepted as of the date referred to above,

     CELGENE CORPORATION

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title:
           --------------------------------


     JOHN HANCOCK MUTUAL LIFE INSURANCE COMPANY

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title:
           --------------------------------

     JOHN HANCOCK VARIABLE LIFE INSURANCE COMPANY

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title:
           --------------------------------

     SIGNATURE lA (CAYMAN), LTD.
     By: John Hancock Mutual Life Insurance
           Company, Portfolio Advisor

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title:
           --------------------------------







                 Signature Page of Registration Rights Agreement

            Agreed to and accepted as of the date referred to above.


     CELGENE CORPORATION

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title:
           --------------------------------

     JOHN HANCOCK MUTUAL LIFE INSURANCE COMPANY

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title: Senior Investment Officer
           --------------------------------

     JOHN HANCOCK VARIABLE LIFE INSURANCE COMPANY

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title: Senior Investment Officer
           --------------------------------

     SIGNATURE lA (CAYMAN), LTD.
     By: John Hancock Mutual Life Insurance
     Company, Portfolio Advisor

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title: Senior Investment Officer
           --------------------------------




            Signature Page of Registration Rights Agreement Continued

Signature 3 Limited
By: John Hancock Mutual Life Insurance Company,
         as Portfolio Advisor

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title:  Senior Investment Officer
           --------------------------------

Hancock Mezzanine Partners L.P.
By: Hancock Mezzanine Investments LLC, its General Partner
By: John Hancock Mutual Life Insurance Company.
                  as Investment Manager

     By:
        -----------------------------------
     Name:
          ---------------------------------
     Title: Senior Investment Officer
           --------------------------------