EXHIBIT 99.1

                         LA JOLLA PHARMACEUTICAL COMPANY
                  REPORTS FIRST QUARTER 2005 FINANCIAL RESULTS

SAN DIEGO, MAY 5, 2005 -- La Jolla Pharmaceutical Company (Nasdaq: LJPC)
reported a net loss for the first quarter ended March 31, 2005 of $9.1 million,
or $0.13 per share (on 69.4 million weighted average shares), compared to a net
loss of $8.4 million, or $0.15 per share (on 54.7 million weighted average
shares), for the first quarter of 2004.

Total operating expenses increased to $9.3 million for the three months ended
March 31, 2005 from $8.3 million for the same period in 2004 primarily due to
termination benefits, mainly severance, of approximately $1.3 million recorded
in March 2005, in connection with the termination of 61 employees.

Research and development expenses increased to $7.3 million for the three months
ended March 31, 2005 from $6.8 million for the same period in 2004 primarily due
to termination benefits, mainly severance, of approximately $0.9 million
recorded in March 2005. In addition, there was an increase in expenses
associated with the clinical benefit trial of Riquent(R), which was initiated in
August 2004. These increases were partially offset by a decrease in expenses
related to the purchase of raw materials for the production of Riquent, the
Company's drug candidate for lupus kidney disease.

Cash, cash equivalents and short-term investments as of March 31, 2005 were
$30.2 million compared to $23.1 million as of December 31, 2004. On February 2,
2005, the Company sold 12,250,000 shares of its common stock in a public
offering for net proceeds, after expenses, of approximately $15.8 million.

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 for the treatment of lupus kidney disease, a leading cause
of sickness and death in patients with lupus. The Company is also 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 Web site: 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 we are seeking collaborative agreements to
support the development of Riquent and our small molecule inflammation program,
we cannot guarantee that we will be successful in establishing any such
collaborative agreements or that the terms of any potential agreements will
result in the payment of significant funds to us. The analyses of clinical
results of Riquent, previously known as LJP 394, our drug candidate for the
treatment of

systemic lupus erythematosus ("lupus") and any other drug candidate that we may
develop, including the results of any trials that are ongoing or that we may
initiate in the future, 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 with respect to the secondary
endpoint, time to treatment with high-dose corticosteroids or cyclophosphamide.
The results from our clinical trials of Riquent, including the results of any
trials that are ongoing or that we may initiate in the future, 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 can be no assurance, however, that we will have
the necessary resources to complete any current or future trials or that any
such trials 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 clinical trials in addition to our current
clinical trial, 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: our clear need for additional financing or a
collaborative agreement; obtaining required regulatory approvals, including
delays associated with any approvals that we may obtain; our ability to pass all
necessary FDA inspections; 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, 2004, 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,
                                                         (UNAUDITED)
                                                    2005            2004
                                                 --------------------------
                                                            
 Research and development expense                  $ 7,348         $ 6,801
 General and administrative expense                  1,908           1,518
                                                 -----------      ----------
     Total expenses                                  9,256           8,319

                                                 -----------      ----------
 Loss from operations                               (9,256)         (8,319)

 Interest income (expense), net                        114             (56)

                                                 -----------      ----------
 Net loss                                        $  (9,142)       $ (8,375)
                                                 ===========      ==========

 Basic and diluted net loss per share            $   (0.13)       $  (0.15)
                                                 ===========      ==========

 Shares used in computing basic and diluted
 net loss per share                                 69,405          54,747
                                                 ===========      ==========




 BALANCE SHEET INFORMATION
                                                  MARCH 31,      DECEMBER 31,
                                                    2005             2004
                                                 -----------     -----------
                                                 (UNAUDITED)
                                                            
 ASSETS
 Cash, cash equivalents, and short-term
 investments                                     $  30,203        $ 23,065

 Other assets                                        9,249           9,961

                                                 -----------     -----------
     Total assets                                $  39,452        $ 33,026
                                                 ===========     ===========

 LIABILITIES AND STOCKHOLDERS' EQUITY
 Liabilities                                     $   6,668        $  7,025

 Stockholders' equity                               32,784          26,001

                                                 -----------     -----------
   Total liabilities and stockholders' equity    $  39,452        $ 33,026
                                                 ===========     ===========