EXHIBIT 5.1

                          OPINION OF COOLEY GODWARD LLP

February 5, 2001


Inhale Therapeutic Systems, Inc.
150 Industrial Road
San Carlos, CA 94070

Ladies and Gentlemen:

You have requested our opinion with respect to certain matters in connection
with the filing by Inhale Therapeutic Systems, Inc, a Delaware corporation (the
"Company"), of a Registration Statement on Form S-8 (the "Registration
Statement") with the Securities and Exchange Commission (the "Commission")
covering up to 82,283 shares of the Company's Common Stock, $.001 par value (the
"Shares"), for issuance pursuant to the Company's assumption of such options
issued under the Bradford Particle Design plc Approved Employee Share Option
Scheme, The Bradford Particle Design plc Unapproved Employee Share Option
Scheme, that certain Agreement Granting Options between Mr. Joseph F. Bohan and
Bradford Particle Design plc dated November 5, 1999, that certain Agreement
Granting Options between Mr. Joseph F. Bohan and Bradford Particle Design plc
dated October 27, 2000, that certain Agreement Granting Options between Dr.
Boris Shekunov and Bradford Particle Design plc dated October 13, 1999 and that
certain Agreement Granting Options between Mrs. Madge Hollowood and Bradford
Particle Design plc dated October 13, 1999 (collectively, the "Option
Agreements") and assumed pursuant to the terms of the Purchase Offer by which
the Company acquired all of the issued share capital of Bradford effective
January 8, 2001.

In connection with this opinion, we have examined and relied upon the
Registration Statement and related Prospectus, the Company's Certificate of
Incorporation, as amended, and Bylaws, as currently in effect, 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, 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 Registration
Statement and the Option Agreements, and the options granted thereunder will
be validly issued, fully paid and non-assessable.

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

Very truly yours,

COOLEY GODWARD LLP


/s/ Mark P. Tanoury
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Mark P. Tanoury