EXHIBIT 5.1


                         OPINION OF LATHAM & WATKINS LLP

                          [Latham & Watkins Letterhead]

December 5, 2007


Geron Corporation
230 Constitution Drive
Menlo Park, CA 94025


     Re:  REGISTRATION  OF 349,138 SHARES OF COMMON STOCK,  PAR VALUE $0.001 PER
          SHARE, OF GERON CORPORATION,  PURSUANT TO A REGISTRATION  STATEMENT ON
          FORM S-3

Ladies and Gentlemen:

      We have acted as special counsel to Geron Corporation, a Delaware
corporation (the "Company"), in connection with the registration for resale of
(i) 85,546 shares of common stock, par value $0.001 per share (the "Hongene
Shares"), to be issued to Hongene Biotechnology Limited ("Hongene") pursuant to
the Common Stock Purchase Agreement, dated as of November 21, 2007, by and
between the Company and Hongene (the "Hongene Agreement"), (ii) 116,099 shares
of common stock, par value $0.001 per share (the "Girindus Shares"), to be
issued to Girindus America Inc. ("Girindus") pursuant to the Common Stock
Purchase Agreement, dated as of November 26, 2007 by and between the Company and
Girindus (the "Girindus Agreement") and (iii) 147,493 shares of common stock,
par value $0.001 per share (the "Lonza Shares" and, collectively with the
Hongene Shares and the Girindus Shares, the "Shares"), to be issued to Lonza
Walkersville, Inc. ("Lonza") pursuant to the Common Stock Purchase Agreement,
dated as of November 21, 2007, by and between the Company and Lonza (the "Lonza
Agreement" and, collectively with the Hongene Agreement and the Girindus
Agreement, the "Agreements"), pursuant to a registration statement on Form S-3
under the Securities Act of 1933, as amended (the "Act"), to be filed with the
Securities and Exchange Commission (the "Commission") on December 5, 2007 (the
"Registration Statement"). This opinion is being furnished pursuant to the
requirements of Item 601(b)(5) of Regulation S-K under the Act, and no opinion
is expressed herein as to any matter pertaining to the contents of the
Registration Statement or the prospectus forming a part thereof (the
"Prospectus"), other than as expressly stated herein with respect to the
validity of the Shares.

      As such counsel, we have examined such matters of fact and questions of
law as we have considered appropriate for purposes of this letter. With your
consent, we have relied upon the foregoing and upon certificates and other
assurances of officers of the Company and others as to factual matters without
having independently verified such factual matters.

      We are opining herein only as to the General Corporation Law of the State
of Delaware, and we express no opinion with respect to any other laws.

      Subject to the foregoing and the other matters set forth herein, it is our
opinion that, as of the date hereof, when certificates representing the Shares
in the form of the specimen certificate filed as an exhibit to the registration
statement filed on Form S-1 (Registration No. 333-05853) have been manually
signed by an authorized officer of the transfer agent and registrar therefor,
and have been delivered to and paid for in the circumstances contemplated by the
Agreements, the issuance and sale of the Shares will have been duly authorized
by all necessary corporate action of the Company, and the Shares will be validly
issued, fully paid and nonassessable.

      This opinion is for your benefit in connection with the Registration
Statement and may be relied upon by you and by persons entitled to rely upon it
pursuant to the applicable provisions of the Act. We consent to your filing this
opinion as an exhibit to the Registration Statement and to the reference to our
firm in the Prospectus under the heading "Legal Matters." In giving such
consent, we do not thereby admit that we are in the category of persons whose
consent is required under Section 7 of the Act or the rules and regulations of
the Commission thereunder.

                                    Very truly yours,
                                    /s/ Latham & Watkins LLP