Exhibit 99.1

                Tesoro Provides First Quarter Earnings Guidance

    SAN ANTONIO--(BUSINESS WIRE)--April 12, 2004--Tesoro Petroleum
Corporation (NYSE:TSO) announced today that it expects to earn around
$0.70 per share for the first quarter. Stronger refining margins,
higher throughput volumes, and lower interest expense are the primary
reasons for the expected earnings improvement compared to the first
quarter of last year.
    Included in the first quarter's expectation is an after-tax charge
of $0.02 per share related to the successful completion of the
company's consent solicitation relating to its 8% Senior Secured Notes
due 2008. The amendment allows Tesoro to exempt all repayments that
may be made with respect to its $300 million 9% Senior Subordinated
Notes due 2008 from the restrictions in the indenture and credit and
guaranty agreement.
    Tesoro Petroleum Corporation, a Fortune 500 Company, is an
independent refiner and marketer of petroleum products. Tesoro
operates six refineries in the western United States with a combined
capacity of nearly 560,000 barrels per day. Tesoro's retail-marketing
system includes approximately 560 branded retail stations, of which
over 200 are company operated under the Tesoro(R) and Mirastar(R)
brands.

    This news release contains certain statements that are
"forward-looking" statements within the meaning of Section 27A of the
Securities Act of 1933 and Section 21E of the Securities Exchange Act
of 1934. These forward-looking statements contain expectations with
respect to the company's first quarter earnings, refining margins,
throughput volumes, interest expense, and charges related to the
Company's consent solicitation regarding its 8% Senior Secured Notes
due 2008. Factors which may cause actual results to differ from those
forward-looking statements include: changes in general economic
conditions, worldwide political developments, the timing and extent of
changes in demand for refined products, availability and cost of crude
oil, other feedstocks, or of refined products, the price differentials
between light and heavy crude oils and light and heavy refined
products, throughput and yield levels, disruptions due to equipment
interruptions or failure at Company or third-party facilities, and
other factors beyond the Company's control. For more information
concerning factors that could cause such a difference, see the
company's annual report on Form 10-K and quarterly reports on Form
10-Q filed with the Securities and Exchange Commission. The company
undertakes no obligation to publicly release the result of any
revisions to any such forward-looking statements that may be made to
reflect events or circumstances that occur, or which the Company
becomes aware of, after the date hereof.

    CONTACT: Tesoro Petroleum Corporation, San Antonio
             Investors:
             John Robertson, 210-283-2687
             or
             Media:
             Tara Ford Payne, 210-283-2676