EXHIBIT 5.1

                 [LETTERHEAD OF CAHILL GORDON & REINDEL]


                            September 4, 1997

                                                            (212) 701-3000

XOMA Corporation
2910 Seventh Street
Berkeley, California 94710

Ladies and Gentlemen:

     As counsel for XOMA Corporation (the "Company"), we are representing the
Company in connection with the registration statement on Form S-3 (the
"Registration Statement") filed with the Securities and Exchange Commission (the
"Commission"), relating to the registration under the Securities Act of 1933, as
amended (the "Act"), of 3,800,000 shares (the "Shares") of the Company's Common
Stock, par value $.0005 per share.

     We advise you that in our opinion the Shares, when issued in the manner and
for the consideration contemplated by the Registration Statement, will be
validly issued, fully paid and non-assessable.

     We hereby consent to the filing of this opinion with the Commission as an
exhibit to the Registration Statement. We also consent to the reference under
the heading "Legal Opinions" in the Registration Statement to our having passed
upon the legal matters referred to above. Our consent to such reference does not
constitute a consent under Section 7 of the Act, as in consenting to such
reference we have not certified any part of the Registration Statement and do
not otherwise come within the categories of persons whose consent is required
under said Section 7 or under the rules and regulations of the Commission
thereunder.

                                    Very truly yours,


                                    CAHILL GORDON & REINDEL