Exhibit 5.1

[Cooley Godward LLP Letterhead]

July 13, 2006

Genelabs Technologies, Inc.
505 Penobscot Drive
Redwood City, California 94063

Re:      Genelabs Technologies, Inc.

Ladies and Gentlemen:

You have requested our opinion with respect to certain matters in connection with the filing by Genelabs Technologies, Inc. (the “Company”) of a registration statement on Form S-3 (the “Registration Statement”) with the Securities and Exchange Commission, including a prospectus covering the resale of up to 6,122,447 shares of common stock of the Company issued pursuant to that certain Securities Purchase Agreement dated June 27, 2006 (the “Agreement Shares”), and up to 2,448,974 shares of the Company’s common stock (the “Warrant Shares”) issuable upon the exercise of warrants to purchase common stock of the Company (the “Warrants”), which in each case are held by certain shareholders named in such prospectus.

In connection with this opinion, we have examined the Registration Statement and related prospectus, the Company’s Amended and Restated Certificate of Incorporation and Bylaws, each 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.

Based on the foregoing, and in reliance thereon, we are of the opinion that (i) the Agreement Shares have been validly issued and are fully paid and non-assessable and (ii) if, as, and when the Warrant Shares are issued and delivered by the Company in accordance with the terms of the Warrants, including, without limitation, the payment in full of applicable consideration, the Warrant Shares 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/ Brett D. White

Brett D. White