EXHIBIT 5.1


                          [COOLEY GODWARD LETTERHEAD]



February 11, 2002


                                                            www.cooley.com

Amylin Pharmaceuticals, Inc.                                THOMAS A COLL
9373 Towne Centre Drive                                     858 550-6013
San Diego, CA 92121                                         coll@cooley.com


Ladies and Gentlemen:

You have requested our opinion with respect to certain matters in connection
with the underwritten public offering by Amylin Pharmaceuticals, Inc., a
Delaware corporation (the "Company"), of up to 12,075,000 shares of the
Company's common stock, par value $0.001 (the "Shares"), including 1,575,000
shares of common stock for which the underwriters have been granted an
over-allotment option, pursuant to a Registration Statement on Form S-3 and the
related Prospectus and Prospectus Supplement filed with the Securities and
Exchange Commission. All of the Shares are to be sold by the Company as
described in the Registration Statement and related Prospectus and Prospectus
Supplement.

In connection with this opinion, we have examined and relied upon the
Registration Statement and related Prospectus and Prospectus Supplement included
therein, the Company's certificate of incorporation and bylaws, as amended, and
the originals or copies certified to our satisfaction of such records,
documents, certificates, memoranda and other instruments as in our judgment are
necessary or appropriate to enable us to render the opinion expressed below. We
have assumed the genuineness and authenticity of all documents submitted to us
as originals, and the conformity to originals of all documents where due
execution and delivery are a prerequisite to the effectiveness thereof.

On the basis of the foregoing, and in reliance thereon, we are of the opinion
that the Shares, when sold in accordance with the Registration Statement and
related Prospectus and Prospectus Supplement, will be validly issued, fully paid
and nonassessable.


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We consent to the reference to our firm under the caption "Legal Matters" in the
Prospectus and Prospectus Supplement included in the Registration Statement and
to the filing of this opinion as an exhibit to the Registration Statement.

Very truly yours,

Cooley Godward LLP

By: /s/ Thomas A. Coll
   --------------------------------
           Thomas A. Coll