EXHIBIT 5.1


                       [LETTERHEAD OF LATHAM & WATKINS]


                                       November 3, 2000


Amgen Inc.
One Amgen Center Drive
Thousand Oaks, California 91320-1799

          Re:  Registration Statement on Form S-4 of Common Stock,
               $.0001 par value per share
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Ladies and Gentlemen:

          In connection with the registration under the Securities Act of 1933,
as amended (the "Act"), by Amgen Inc., a Delaware corporation (the "Company"),
on Form S-4 filed with the Securities and Exchange Commission (the "Commission")
on November 3, 2000 (the "Registration Statement"), of that certain number of
shares of common stock of the Company, par value $.0001 per share (the
"Shares"), having a value equal to the Actual Aggregate Consideration (as
defined in the Agreement and Plan of Merger among the Company, Kinetix
Pharmaceuticals Inc. and Amgen Acquisition Corp. II, dated October 16, 2000 (the
"Merger Agreement")), you have requested our opinion with respect to the matters
set forth below.

          In our capacity as your counsel in connection with such registration,
we are familiar with the proceedings taken and proposed to be taken by the
Company in connection with the authorization, issuance and sale of the Shares,
and for the purposes of this opinion, have assumed such proceedings will be
timely completed in the manner presently proposed. In addition, we have made
such legal and factual examinations and inquiries, including an examination of
originals or copies certified or otherwise identified to our satisfaction of
such documents, corporate records and instruments, as we have deemed necessary
or appropriate for purposes of this opinion.

          In our examination, we have assumed the genuineness of all signatures,
the authenticity of all documents submitted to us as originals, and the
conformity to authentic original documents of all documents submitted to us as
copies.

          We are opining herein as to the effect on the subject transaction only
of the General Corporation Law of the State of Delaware, and we express no
opinion with respect to the applicability thereto, or the effect thereon, of the
laws of any other jurisdiction or, in the case of Delaware, any other laws, or
as to any matters of municipal law or the laws of any local agencies within any
state.

          Subject to the foregoing, it is our opinion that the Shares have been
duly authorized, and, upon issuance in the manner contemplated by the Merger
Agreement and the Registration Statement, will be validly issued, fully paid and
nonassessable.

          We consent to your filing this opinion as an exhibit to the
Registration Statement and to the reference to our firm contained under the
heading "Legal Matters".


                                       Very truly yours,


                                       /s/ Latham & Watkins