EXHIBIT 5.1



[COOLEY GODWARD LETTERHEAD]

April 25, 2001


Tularik Inc.
Two Corporate Drive
South San Francisco, CA 94080

Ladies and Gentlemen:

You have requested our opinion with respect to certain matters in connection
with the filing by Tularik Inc. (the "Company") of a Registration Statement on
Form S-8 (the "Registration Statement") with the Securities and Exchange
Commission covering the offering of up to 2,166,690 shares of the Company's
Common Stock, $0.001 par value (the "Shares"), with respect to the Company's
1997 Equity Incentive Plan and 1999 Employee Stock Purchase Plan (the "Plans").

In connection with this opinion, we have examined the Registration Statement,
your Certificate of Incorporation and Bylaws, as amended, and such other
documents, records, certificates, memoranda and other instruments as we deem
necessary as a basis for this opinion. 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
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 and issued in accordance with the Plans and the
Registration Statement, will be validly issued, fully paid and nonassessable
(except as to shares issued pursuant to certain deferred payment arrangements,
which will be fully paid and nonassessable when such deferred payments are made
in full).

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

Very truly yours,

COOLEY GODWARD LLP

By:
           /s/ Suzanne Sawochka Hooper
        -----------------------------------
        Suzanne Sawochka Hooper, Esq.