EXHIBIT 32.1

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

Each of the undersigned, in his or her capacity as an officer of La Jolla
Pharmaceutical Company (the "Registrant"), hereby certifies, for purposes of 18
U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley
Act of 2002, that:

      -     the annual report of the Registrant on Form 10-K for the year ended
            December 31, 2004 (the "Report"), which accompanies this
            certification, fully complies with the requirements of Section 13(a)
            or 15(d) of the Securities Exchange Act of 1934; and

      -     the information contained in the Report fairly presents, in all
            material respects, the financial condition of the Registrant at the
            end of such year and the results of operations of the Registrant of
            such year.

Dated: March 9, 2005

                                     /s/ Steven B. Engle
                                     ------------------------------------------
                                     Steven B. Engle
                                     Chairman and Chief Executive Officer

                                     /s/ Gail A. Sloan
                                     ------------------------------------------
                                     Gail A. Sloan
                                     Vice President of Finance and Secretary

Note: A signed original of this written statement required by Section 906 has
      been provided to La Jolla Pharmaceutical Company and will be retained by
      La Jolla Pharmaceutical Company and furnished to the Securities and
      Exchange Commission or its staff upon request.