EXHIBIT 99.1


                         LA JOLLA PHARMACEUTICAL COMPANY
                  REPORTS FIRST QUARTER 2004 FINANCIAL RESULTS

SAN DIEGO, MAY 6, 2004 -- La Jolla Pharmaceutical Company (Nasdaq: LJPC)
reported a net loss for the first quarter ended March 31, 2004 of $8.4 million,
or $0.15 per share (on 54.7 million weighted average shares), compared to a net
loss of $13.5 million, or $0.32 per share (on 42.5 million weighted average
shares), for the first quarter of 2003.

Research and development expenses decreased to $6.8 million for the three months
ended March 31, 2004 from $11.9 million for the same period in 2003 primarily
due to a decrease in expenses related to the Company's open-label follow-on
clinical trial of Riquent(R) which was closed in April 2003, a decrease in
expenses related to the unblinding and analysis of the data from the Company's
Phase 3 trial of Riquent in the first quarter of 2003 and a decrease in
personnel costs related to the organizational restructuring that occurred in May
2003.


Cash, cash equivalents and short-term investments as of March 31, 2004 were
$53.7 million compared to $32.1 million as of December 31, 2003. In February and
March 2004, the Company sold an aggregate of 10.0 million shares of its common
stock in a public offering for net proceeds, after expenses, of approximately
$29.4 million. The Company anticipates that its existing cash, cash investments
and interest earned thereon will be sufficient to fund the Company's operations
as currently planned into the second quarter of 2005, assuming that the Company
does not engage in any significant clinical trial or commercialization
activities and further assuming that the Company does not enter into an
agreement with a collaborative partner or engage in any other fundraising
activities.

La Jolla Pharmaceutical Company is a biotechnology company developing
therapeutics for antibody-mediated autoimmune diseases and inflammation
afflicting several million people in the United States and Europe. The Company
is developing Riquent(R) 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, and is in the early stage of developing small
molecules to treat various other autoimmune and inflammatory conditions. The
Company's common stock is traded on The Nasdaq Stock Market under the symbol
LJPC. For more information about the Company, visit its website at
http://www.ljpc.com.

The forward-looking statements in this press release involve 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 that express a plan, belief, expectation, estimation,
anticipation, intent, contingency, future development or similar expression.
Although our New Drug Application ("NDA") for Riquent(R) has been accepted by
the United States Food and Drug Administration (the "FDA") for review, there is
no guarantee that the FDA 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 showed that the trial did not reach statistical significance with
respect to its primary endpoint, time to renal flare, or to the secondary
endpoint, time to treatment with high-dose corticosteroids or cyclophosphamide.
Although our NDA for Riquent has been accepted for review by the FDA, the
results from our clinical trials of Riquent may not ultimately be sufficient to
obtain regulatory clearance to market Riquent either in the United States 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
and will likely be reviewed as part of the Riquent approval process. 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 adversely 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; our ability to pass FDA pre-approval inspections
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; our ability to make use of the orphan drug designation for
Riquent; 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, 2003, and in other reports and registration statements that
we file with the Securities and Exchange Commission from time to time.


                                       ###



LA JOLLA PHARMACEUTICAL COMPANY
CONDENSED FINANCIAL STATEMENTS (IN THOUSANDS EXCEPT PER SHARE DATA)

SUMMARY OF OPERATIONS



                                                                 THREE MONTHS ENDED
                                                                      MARCH 31,
                                                                  2004        2003
                                                                --------    --------
                                                                      
Research and development expense                                $  6,801    $ 11,920
General and administrative expense                                 1,518       1,801
                                                                --------    --------
    Total expenses                                                 8,319      13,721
                                                                --------    --------
Loss from operations                                              (8,319)    (13,721)

Interest (expense) income, net                                       (56)        180
                                                                --------    --------
Net loss                                                        $ (8,375)   $(13,541)
                                                                ========    ========
Basic and diluted net loss per share                            $  (0.15)   $  (0.32)
                                                                ========    ========
Shares used in computing basic and diluted net loss per share     54,747      42,480
                                                                ========    ========


BALANCE SHEET INFORMATION


                                                                MARCH 31,  DECEMBER 31,
                                                                  2004        2003
                                                                ---------  ------------
                                                                      
ASSETS

Cash, cash equivalents, and short-term investments              $ 53,697    $ 32,133
Other assets                                                      10,037       9,811
                                                                --------    --------
    Total assets                                                $ 63,734    $ 41,944
                                                                ========    ========

LIABILITIES AND STOCKHOLDERS' EQUITY

Liabilities                                                     $  6,149    $  5,517
Stockholders' equity                                              57,585      36,427
                                                                --------    --------
    Total liabilities and stockholders' equity                  $ 63,734    $ 41,944
                                                                ========    ========