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                                                                   EXHIBIT 5.1


October 19, 1998



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

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 covering the offering 
of up to 775,000 shares of the Company's Common Stock, $0.0001 par value (the 
"SHARES"), pursuant to its 1998 Non-Officer Equity Incentive Plan (the 
"PLAN").

In connection with this opinion, we have examined the Registration Statement 
and related Prospectus, your Certificate of Incorporation and By-laws, 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 Plan, the 
Registration Statement and related Prospectus, 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/ MARK P. TANOURY           
     ------------------------------
     Mark P. Tanoury


