EXHIBIT 5 [Letterhead of Latham & Watkins] September 2, 1998 Amgen Inc. One Amgen Center Drive Thousand Oaks, California 91320-1789 Re: Amgen Inc. Common Stock, par value $.0001 per share Registration on Form S-8 ---------------------------------------- Ladies and Gentlemen: At your request, we have examined the Registration Statement on Form S-8 (the "Registration Statement"), which you intend to file with the Securities and Exchange Commission in connection with the registration under the Securities Act of 1933, as amended, of an aggregate of 9,000,000 shares of Common Stock, par value $.0001 per share (the "Shares"), to be sold by Amgen Inc. (the "Company") under the Amended and Restated 1997 Special Non-Officer Equity Participation Plan (the "Plan"). We are familiar with the proceedings undertaken in connection with the authorization and proposed issuance and sale of the Shares. Additionally, we have examined such questions of law and fact as we have considered necessary or appropriate for purposes of this opinion. Based upon the foregoing, we are of the opinion that the Shares have been duly authorized, and upon the issuance of Shares under the terms of the Plan and delivery and payment therefor of legal consideration in excess of the aggregate par value of the Shares issued, such Shares will be validly issued, fully paid and nonassessable. We consent to your filing this opinion as an exhibit to the Registration Statement. Very truly yours, /s/ Latham & Watkins Page 19 of page 20