EXHIBIT 99.1

FOR IMMEDIATE RELEASE

                                         CONTACT:   ROBERT J. HUGIN
                                                    CELGENE CORPORATION
                                                    SENIOR VICE PRESIDENT  & CFO
                                                    (732) 271-4102



                 CELGENE CORPORATION INCREASES SIZE OF PROPOSED
                              COMMON STOCK OFFERING

WARREN, NJ (FEBRUARY 8, 2000) - Celgene Corporation (NASD: CELG) today announced
that it intends to amend its registration  statement  currently on file with the
Securities and Exchange  Commission to increase the size of its proposed  common
stock offering to 3,000,000 shares. Of the shares, 2,484,000 shares will be sold
by Celgene for its own account.  The  remaining  516,000  shares will be sold by
John Hancock Life Insurance Company and its affiliates.  Celgene will also grant
to the underwriters an option to purchase an additional 450,000 shares of common
stock to cover over-allotments.

Celgene   Corporation,   headquartered   in  Warren,   NJ,  is  an   independent
biopharmaceutical   company   engaged   in  the   discovery,   development   and
commercialization of small molecule drugs for cancer and immunological diseases.

A registration  statement  relating to these  securities has been filed with the
Securities  and  Exchange  Commission  but has not yet become  effective.  These
securities may not be sold, nor may offers to buy be accepted, prior to the time
the  registration  statement  becomes  effective.  This  announcement  shall not
constitute  an offer to sell or the  solicitation  of an offer to buy, nor shall
there  be any sale of  these  securities  in any  state  in  which  such  offer,
solicitation or sale would be unlawful prior to  registration  or  qualification
under the securities laws of any such state.

This release contains certain forward-looking statements which involve known and
unknown risks,  delays,  uncertainties and other factors not under the Company's
control  which may cause actual  results,  performance  or  achievements  of the
Company  to be  materially  different  from the  results,  performance  or other
expectations implied by these forward-looking statements.  These factors include
but are not limited to actions by the FDA and other regulatory authorities,  the
success of clinical  trials,  potential  future uses of the Company's drugs, and
increased sales revenue for the Company's  products,  and those factors detailed
in the Company's  filings with the  Securities and Exchange  Commission  such as
10K, 10Q, and 8K reports.

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