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                                  EXHIBIT 99.1


April 13, 2000
Andrew Wiseman, Ph.D.

                                   IMMEDIATE

               LA JOLLA PHARMACEUTICAL WILL FILE TO REGISTER STOCK
                  RELATED TO UPCOMING WARRANT EXERCISE DEADLINE

San Diego, April 13, 2000 - La Jolla Pharmaceutical Company (Nasdaq: LJPC)
announced today that it will file a registration statement to register for
resale the underlying shares of common stock for the Company's privately held
warrants. The Company previously registered the underlying shares for its
publicly held warrants following its initial public offering in 1994. The
warrants, as well as an option granted to the underwriter of the Company's
initial public offering, will expire on June 3, 2000. The Company's Board of
Directors does not plan to extend the expiration date.

The Company's public warrants (LJPCW) have an exercise price of $3.00 per
one-half share; two warrants must be exercised with an aggregate exercise price
of $6.00 to purchase one whole share of common stock. The Company has the option
to call the warrants for five cents per warrant if the common stock trades at
greater than $9.00 per share for 20 consecutive trading days, provided that the
Company has notified warrant holders in writing at least 30 days in advance of
calling the warrants.

For further information concerning the exercise of the Company's public
warrants, warrant holders may contact Grace Deer-Loiseau at The American Stock
Transfer & Trust Company, 40 Wall Street, New York, NY 10005 or by calling
718-921-8247. Holders of the Company's private warrants will receive a letter
from the Company shortly that will provide additional information concerning the
exercise of these warrants. In the meantime, holders of the private warrants may
contact the Company. The terms of the Company's warrants, including exercise
prices, remain unchanged.

Until the registration statement covering the common stock to be issued on the
exercise of the private warrants has been declared effective by the SEC, the
common stock will not have been registered under the Securities Act and may not
be offered or sold in the United States absent registration or an applicable
exemption from registration requirements; this press release does not constitute
an offer of securities for sale.



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La Jolla Pharmaceutical is focused on the research and development of
therapeutic compounds to treat antibody-mediated diseases such as lupus,
antibody-mediated thrombosis--a clotting disorder associated with stroke,
myocardial infarction, deep-vein thrombosis and recurrent fetal loss--and organ
rejection in xenotransplantation. The Company develops disease-specific
therapeutics using its proprietary Tolerance Technology(R) for major diseases
and conditions caused by antibodies. By treating the underlying cause of
disease, the Company believes that Tolerance Technology will lead to products
with improved therapeutic benefit and fewer side effects than currently
available treatments. The Company's common stock and warrants trade on The
Nasdaq Stock Market under the symbols LJPC and LJPCW, respectively. For more
information about the Company, visit our website: www.ljpc.com.

Statements in this press release discuss future expectations, contain
projections or state other forward-looking information. These statements involve
risks and uncertainties, and a number of factors, both foreseen and unforeseen,
could cause actual results to be materially different from those contemplated by
the forward-looking statements. In particular, the registration statement to be
filed by the Company with the SEC concerning its private warrants may not be
declared effective by the SEC for some time, if at all. Interested parties are
urged to review the risks detailed from time to time in La Jolla Pharmaceutical
Company's Securities and Exchange Commission (SEC) filings, including the report
on Form 10-K for the year ended December 31, 1999.

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