Exhibit 99.1

                  LA JOLLA PHARMACEUTICAL COMPANY TO PRESENT AT
                        NEEDHAM BIOTECHNOLOGY CONFERENCE

SAN DIEGO, JUNE 3, 2003 -- La Jolla Pharmaceutical Company (Nasdaq: LJPC)
announced today that its Chairman and Chief Executive Officer, Steven B. Engle,
will present at the Needham & Company Second Annual Biotechnology Conference at
the New York Palace Hotel in New York City. Mr. Engle will present on Friday,
June 6, 2003 at 11:00 a.m. eastern time. The presentation will be webcast via
Wall Street Webcasting. Those wishing to access the presentation may link to it
from http://www.ljpc.com or type http://www.twst.com/econf/mm/needham5/ljpc.html
into their browser.

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 our Web site: http://www.ljpc.com.

Except for historical statements, this press release contains 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. Although we have determined to submit a 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 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, will likely
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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