Exhibit 99.1

                   Mentor Graphics Expects Weak First Quarter

    WILSONVILLE, Ore.--(BUSINESS WIRE)--April 4, 2005--Mentor Graphics
Corporation (Nasdaq:MENT) today announced it expects first quarter
revenue to be approximately $165 million and earnings per share before
severance costs and amortization of intangibles to be approximately
break-even. Loss per share on a GAAP basis is expected to be
approximately $.05.
    Company guidance issued on January 27, 2005 was for revenue of
$177 million, earnings per share before severance and amortization of
intangibles of $.05 to $.10, and GAAP earnings per share of $.01 to
$.06.
    "This quarter saw significant year-over-year weakness in all
notable product lines and in all regions," said Walden C. Rhines,
chairman and CEO of Mentor Graphics. "Book-to-bill was extremely weak
and the company consumed substantial backlog."
    The company will announce earnings after market on April 26, 2005
and will review 2005 annual guidance at that time.
    Certain statements in this press release constitute
"forward-looking" statements based on current expectations within the
meaning of Section 21E of the Securities Exchange Act of 1934, as
amended. Such forward-looking statements involve known and unknown
risks, uncertainties and other factors that may cause the actual
results, performance or achievements of the Company to be materially
different from any results, performance or achievements expressed or
implied by such forward-looking statements.

    About Mentor Graphics

    Mentor Graphics Corporation (Nasdaq:MENT) is a world leader in
electronic hardware and software design solutions, providing products,
consulting services and award-winning support for the world's most
successful electronics and semiconductor companies. Established in
1981, the company reported revenues over the last 12 months of over
$700 million and employs approximately 3,850 people worldwide.
Corporate headquarters are located at 8005 S.W. Boeckman Road,
Wilsonville, Oregon 97070-7777; Silicon Valley headquarters are
located at 1001 Ridder Park Drive, San Jose, California 95131-2314.
World Wide Web site: http://www.mentor.com/.

    CONTACT: Mentor Graphics Corporation
             Ryerson Schwark, 503-685-1462
             ry_schwark@mentor.com
             Dennis Weldon, 503-685-1462
             dennis_weldon@mentor.com