EXHIBIT 99.1

    LA JOLLA PHARMACEUTICAL COMPANY PRESENTS FIVE POSTERS AT AMERICAN COLLEGE
                                OF RHEUMATOLOGY


SAN DIEGO, OCTOBER 27, 2003 -- La Jolla Pharmaceutical Company (Nasdaq: LJPC)
announced today that the Company and several of its clinical investigators
presented five posters at the American College of Rheumatology 67th Annual
Scientific Meeting in Orlando, FL. The posters included previously released data
from several of the Company's clinical trials of Riquent(TM) (formerly LJP 394)
for the treatment of lupus renal disease and data regarding LJP 1082, the
Company's drug candidate for the treatment of antibody-mediated thrombosis.

Mario Cardiel, M.D., Department of Immunology and Rheumatology, Instituto
Nacional de la Nutricion Salvador Zubiran, Mexico City, presented a poster
entitled "Clinical Efficacy Results from a Randomized Clinical Trial of LJP 394
in SLE Patients with History of Renal Disease." The poster reviewed data from
the Phase 3 clinical trial of Riquent, in which 298 lupus patients were treated
with Riquent or a placebo for up to 22 months. Treatment with Riquent resulted
in 25% fewer renal flares and 21% fewer Major SLE flares compared with placebo,
although as previously announced these findings were not statistically
significant. Treatment with Riquent also resulted in a statistically significant
reduction in antibodies to double-stranded DNA (dsDNA) that are believed to
cause lupus renal disease. Renal flares are significant increases in kidney
inflammation that can lead to a loss of kidney function, kidney failure, and the
need for long-term dialysis. A Major SLE flare is a composite endpoint of
treatments for lupus, including the initiation or increased use of
immunosuppressive agents, hospitalization or death due to lupus.

Matthew Linnik, Ph.D., La Jolla Pharmaceutical Company's Chief Scientific
Officer and Executive Vice President of Research, presented a poster entitled
"SLE Patients with Sustained Reductions in Anti-dsDNA Antibodies Have a Reduced
Risk of Renal Flare and Major SLE Flare." This poster reviewed data from both
the Phase 3 and Phase 2/3 clinical trials of Riquent, where lupus patients with
sustained reductions in antibodies to dsDNA had a lower incidence of both renal
flare and Major SLE flare. Treatment with Riquent resulted in a two- and
four-fold increase, respectively, in the number of patients with sustained
reductions in antibodies to dsDNA compared with placebo.

Daniel Wallace, M.D., F.A.C.P., F.A.C.R., Clinical Chief of Rheumatology,
Cedars-Sinai Medical Center, Los Angeles, and Clinical Professor, UCLA School of
Medicine, presented a poster entitled "Safety Results from a Randomized
Controlled Trial (RCT) of LJP 394 in Systemic Lupus Erythematosus (SLE) Patients
with a History of Renal Disease." The poster reviewed safety data from the Phase
3 trial of Riquent, which showed no differences in the overall incidence of
serious adverse events or adverse events between Riquent-treated patients and
placebo-treated patients.

Based on the data from the Phase 3 and 2/3 clinical studies, as well as
additional data, La Jolla Pharmaceutical Company currently plans to submit a New
Drug Application for Riquent with the United States Food and Drug Administration
(FDA) in December 2003 or January 2004.

Additionally, La Jolla Pharmaceutical presented two posters regarding LJP 1082,
the Company's drug candidate designed to treat antibody-mediated thrombosis,
also known as Antiphospholipid Syndrome. Arash Horizon, M.D., Division of
Rheumatology, Cedars-Sinai Medical Center, and Assistant Clinical Director,
UCLA, presented a poster entitled "Results of a Randomized, Placebo Controlled,
Double Blind Phase 1/2 Clinical Trial (RCT) to Assess the Safety and
Tolerability of LJP 1082 in Patients with Antiphospholipid Syndrome." The poster
reviewed previously announced and additional data from the Phase 1/2 clinical
trial of LJP 1082 in which 20 patients received placebo or doses of LJP 1082
ranging from 1 to 200 mg. There were no significant safety differences between
drug-treated and placebo-treated patients, and there were no serious adverse
events reported. Trial data also demonstrated that circulating antibodies from
treated patients bound to LJP 1082 in a dose-dependent manner. Patients in the
trial treated with 200 mg showed the highest level of reactivity with LJP 1082.

Dr. Linnik also presented a poster relating to LJP 1082, entitled "Domain
Specificity of Autoantibodies to Beta 2-Glycoprotein 1 in Patients with
Antiphospholipid Syndrome Enrolled in a Phase 1/2 Trial with LJP 1082." The
poster summarized laboratory analyses demonstrating that the antibodies from
most of the 15 patients studied were highly specific for domain 1 of beta-2
glycoprotein 1. These antibodies are believed to contribute to the increased
risk of thrombotic events in Antiphospholipid Syndrome. This study further
supports the development of a domain 1 Toleragen(R) as a treatment for this
disease.

La Jolla Pharmaceutical Company is a biotechnology company developing
therapeutics for antibody-mediated autoimmune diseases afflicting several
million people in the United States and Europe. The Company is developing
Riquent(TM), formerly known as LJP 394, for the treatment of lupus kidney
disease, a leading cause of sickness and death in patients with lupus. The
Company is also developing LJP 1082 for the treatment of antibody-mediated
thrombosis, a condition in which patients suffer from recurrent stroke,
deep-vein thrombosis and other thrombotic events. The Company's common stock is
traded on The Nasdaq Stock Market under the symbol LJPC. For more information
about the Company, visit its Web site: http://www.ljpc.com.

Except for historical statements, this press release contains, and the
presentations referred to above contained, forward-looking statements involving
significant risks and uncertainties, and a number of factors, both foreseen and
unforeseen, could cause actual results to differ materially from our current
expectations. Forward-looking statements include those which express a plan,
belief, expectation, estimation, anticipation, intent, contingency, future
development or similar expression. Although we plan to submit a New Drug
Application ("NDA") for Riquent(TM), there is no guarantee that regulatory
authorities will approve Riquent in a timely manner, or at all. Our analyses of
clinical results of Riquent, previously known as LJP 394, our drug candidate for
the treatment of systemic lupus erythematosus ("lupus"), and LJP 1082, our drug
candidate for the treatment of antibody-mediated thrombosis ("thrombosis"), are
ongoing and could result in a finding that these drug candidates are not
effective in large patient populations, do not provide a meaningful clinical
benefit, or may reveal a potential

safety issue requiring us to develop new candidates. The analysis of the data
from our Phase 3 trial of Riquent has shown that the trial did not reach
statistical significance with respect to its primary endpoint, time to renal
flare. Although we plan to submit an NDA for Riquent, the results from our
clinical trials of Riquent may not ultimately be sufficient to obtain regulatory
clearance to market Riquent either in the U.S. or Europe, and we may be required
to conduct additional clinical studies to demonstrate the safety and efficacy of
Riquent in order to obtain marketing approval. There is no guarantee, however,
that we will have the necessary resources to complete any additional trial, that
we will elect to conduct an additional trial, or that any additional trial will
sufficiently demonstrate the safety and efficacy of Riquent. Our blood test to
measure the binding affinity for Riquent is experimental, has not been validated
by independent laboratories, may require regulatory approval, and will likely be
necessary for the approval and the commercialization of Riquent. Our other
potential drug candidates are at earlier stages of development and involve
comparable risks. Analysis of our clinical trials could have negative or
inconclusive results. Any positive results observed to date may not be
indicative of future results. In any event, regulatory authorities may require
additional clinical trials, or may not approve our drugs. Our ability to develop
and sell our products in the future may be affected by the intellectual property
rights of third parties. Additional risk factors include the uncertainty and
timing of: obtaining required regulatory approvals, including delays associated
with any approvals that we may obtain; the clear need for additional financing;
FDA approval of our manufacturing facilities and processes; the increase in
capacity of our manufacturing capabilities for possible commercialization;
successfully marketing and selling our products; our lack of manufacturing,
marketing, and sales experience; generating future revenue from product sales or
other sources such as collaborative relationships; future profitability; and our
dependence on patents and other proprietary rights. Readers are cautioned to not
place undue reliance upon forward-looking statements, which speak only as of the
date hereof, and we undertake no obligation to update forward-looking statements
to reflect events or circumstances occurring after the date hereof. Interested
parties are urged to review the risks described in our Annual Report on Form
10-K for the year ended December 31, 2002, and in other reports and registration
statements that we file with the Securities and Exchange Commission from time to
time.

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