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                                                                     EXHIBIT 5.1

                               September 14, 2001

LSI Logic Corporation
1551 McCarthy Blvd.
Milpitas, CA  95035

         RE:  REGISTRATION STATEMENT ON FORM S-8

Ladies and Gentlemen:

         We have acted as counsel to LSI Logic Corporation, a Delaware
corporation (the "Company" or "you") and have examined the Registration
Statement on Form S-8 (the "Registration Statement") to be filed by you with the
Securities and Exchange Commission on or about September 14, 2001 in connection
with the registration under the Securities Act of 1933, as amended (the "Act"),
of 13,000,000 shares of your Common Stock (the "Shares"), reserved for issuance
under the LSI Logic Corporation 1999 Non Statutory Stock Option Plan (the
"Plan"). As your legal counsel, we have examined the Restated Certificate of
Incorporation and Bylaws of the Company, the Plan and such other documents of
the Company as we have deemed necessary or appropriate for the purposes of
expressing an opinion, and are familiar with the proceedings proposed to be
taken by you in connection with the issuance and sale of the Shares pursuant to
the Plan.

         It is our opinion that, upon completion of the proceedings to be taken
prior to issuance of the Shares, the Shares, when issued and sold in the manner
referred to in the Plan and the agreements which accompany the Plan, in
accordance with the Restated Certificate of Incorporation, will be legally and
validly issued, fully paid and nonassessable.

         We consent to the use of this opinion as an exhibit to the Registration
Statement, and further consent to the use of our name wherever appearing in the
Registration Statement, including the Prospectus constituting a part thereof,
and any amendments thereto.

                                    Sincerely,

                                    /s/ Wilson Sonsini Goodrich & Rosati

                                    WILSON SONSINI GOODRICH & ROSATI
                                    Professional Corporation