EXHIBIT 5.1


                         OPINION OF LATHAM & WATKINS LLP

                          [Latham & Watkins Letterhead]

October 21, 2008

Geron Corporation
230 Constitution Drive
Menlo Park, CA 94025


Re:   REGISTRATION OF 255,754 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
255,754 shares of common stock, par value $0.001 per share (the "Shares"),
issued to Lonza Walkersville, Inc. ("Lonza") pursuant to a Common Stock Purchase
Agreement, dated as of October 3, 2008, by and between the Company and Lonza,
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 October 21, 2008 (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, the issuance and sale of the Shares
have been duly authorized by all necessary corporate action of the Company, and
the Shares are 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