EXHIBIT 5.1 [LETTERHEAD] July 15, 1997 Zitel Corporation 1324 Chesapeake Terrace Sunnyvale, CA 94089 Ladies and Gentlemen: You have requested our opinion with respect to certain matters in connection with the filing by Zitel Corporation (the "Company") of a Registration Statement on Form S-3 (the "Registration Statement") with the Securities and Exchange Commission covering the offering of 3,061,401 shares of the Company's Common Stock, with a par value of $0.001 of which 61,401 shares are currently owned by one of the Selling Securityholders (the "Shares") and up to 3,000,000 (the "Conversion Shares") of which are issuable upon the conversion of the Company's outstanding 5% Convertible Subordinated Debentures (the "Debentures"). In connection with this opinion, we have examined the Registration Statement, the Company's Certificate of Incorporation and Amended and Restated Bylaws, 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 Common Shares are validly issued, fully paid, and nonassessable and that Conversion Shares, when issued upon conversion of the Debentures in accordance with the terms thereof, will be validly issued, fully paid and nonassessable. We consent to the filing of this opinion as an exhibit to the Registration Statement and to the reference to our firm under the caption "Legal Matters" in the Prospectus included in the Registration Statement. Very truly yours, Cooley Godward LLP /s/ John L. Cardoza