EXHIBIT 32.1


                CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350

In connection with the accompanying Quarterly Report on Form 10Q of Celgene
Corporation ("the Company") for the period ended June 30, 2003 ("the Periodic
Report"), I, John W. Jackson, Chief Executive Officer of the Company, hereby
certify pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906
of the Sarbanes-Oxley Act of 2002, to the best of my knowledge that the Periodic
Report fully complies with the requirements of Section 13 (a) or 15 (d) of the
Securities Exchange Act of 1934 and that the information contained in the
Periodic Report fairly presents, in all material respects, the financial
condition and results of operations of the Company.

Date: August 14, 2003                                  /s/ John W. Jackson
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                                                        John W. Jackson
                                                        Chief Executive Officer