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                                                                     Exhibit 5.1


                        [COOLEY GODWARD LLP LETTERHEAD]




July 31, 1998



Coulter Pharmaceutical, Inc.
550 California Avenue, Suite 200
Palo Alto, California 94306-1440

Ladies and Gentlemen:

You have requested our opinion with respect to certain matters in connection
with the filing by Coulter Pharmaceutical, Inc. (the "Company") of a
Post-Effective Amendment, pursuant to Rule 462(b), to the Registration
Statement on Form S-3 filed with the Securities and Exchange Commission on July
10, 1998, as amended (the "Registration Statement"). The Post-Effective
Amendment covers the offering of up to Four Hundred Sixty Thousand (460,000)
shares of the Company's Common Stock, $.001 par value (the "Shares").

In connection with this opinion, we have (i) examined the Registration
Statement and related Prospectus, your Amended and Restated Certificate of
Incorporation and Bylaws, as amended, and such other documents, records,
certificates, memoranda and other instruments as in our judgment are necessary
or appropriate to enable us to render the opinion expressed below, (ii) assumed
that the Amended and Restated Certificate of Incorporation, as set forth in
Exhibit 3.1 of the Registration Statement, shall have been duly approved and
filed with the office of the Delaware Secretary of State, and (iii) assumed
that the shares of Common Stock will be sold by the Underwriters at the price
established by the Pricing Committee of the Board of Directors of the Company.
We have assumed the genuineness and authenticity of all documents submitted to
us as originals, the conformity to originals of all documents submitted to us
as copies thereof, and the due execution and delivery of all documents where
due execution and delivery are a requisite to the effectiveness thereof.

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

We consent to the filing of this opinion as an exhibit to the Registration
Statement.

Very truly yours,

COOLEY GODWARD LLP

/s/ James C. Kitch
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James C. Kitch