EXHIBIT 1 CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS We consent to the incorporation by reference in the Registration Statement (Form S-8 No. 33-39104) pertaining to the Amgen Retirement and Savings Plan of our report dated May 26, 2000, with respect to the financial statements and supplemental schedule of the Amgen Retirement and Savings Plan included in this Annual Report (Form 11-K) for the year ended December 31, 1999. /s/ Ernst & Young LLP Los Angeles, California June 16, 2000