ONYX Pharmaceuticals 10-Q 2002 Q3 Quarterly report

EXHIBIT 99.1

CERTIFICATION

Pursuant to Section 906 of the Public Company Accounting Reform and Investor Protection Act of 2002 (18 U.S.C. § 1350, as adopted), Hollings C. Renton, Chairman of the Board, President and Chief Executive Officer of Onyx Pharmaceuticals, Inc. (the "Company"), hereby certifies that, to the best of his knowledge:

1.             The Company's Quarterly Report on Form 10-Q for the period ended September 30, 2002, to which this Certification is attached as Exhibit 99.1 (the "Periodic Report"), fully complies with the requirements of Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934, as amended; and

2.             The information contained in the Periodic Report fairly presents, in all material respects, the financial condition of the Company at the end of the period covered by the Periodic Report and results of operations of the Company for the period covered by the Periodic Report.

Dated: November 14, 2002

/s/ Hollings C. Renton

Hollings C. Renton

Chairman of the Board, President
and Chief Executive Officer
(Principal Executive and Financial Officer)