EXHIBIT 23.1 CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS As independent public accountants, we hereby consent to the incorporation by reference in this Registration Statement on Form S-3 of our report dated February 3, 1998 included in XOMA Corporation's Form 10-K for the year ended December 31, 1997, and to all references to our firm included in this Registration Statement. ARTHUR ANDERSEN LLP San Francisco, California November 5, 1998