Exhibit 5.1

                                [WSGR Letterhead]


                               October 30, 2003


LSI Logic Corporation
1621 Barber Lane
Milpitas, California  95035

      RE:   REGISTRATION STATEMENT OF FORM S-3

      Ladies and Gentlemen:


      We are acting as counsel for LSI Logic Corporation, a Delaware corporation
(the "Company") in connection with the registration under the Securities Act of
1933, as amended, of $350,000,000 aggregate principal amount of 4.00%
Convertible Senior Subordinated Notes due 2010 (the "Notes"), and 26,080,460
shares of Common Stock initially issuable upon conversion of the Notes, $0.01
par value (the "Common Stock") of the Company under the indenture (collectively,
the "Conversion Shares"). The Notes and the Conversion Shares are to be offered
and sold by certain securityholders of the Company (the "Selling
Securityholders"). In this regard we have participated in the preparation of a
Registration Statement on Form S-3 relating to the Notes and the Conversion
Shares (such Registration Statement, as it may be amended from time to time, is
herein referred to as the "Registration Statement").



      The Notes have been issued pursuant to an Indenture, which has been
incorporated by reference as an exhibit in the Registration Statement, dated as
of May 16, 2003, between the Company and U.S. Bank, National Association, as
trustee (the "Trustee").


      We have examined instruments, documents and records which we deemed
relevant and necessary for the basis of our opinion hereinafter expressed. In
such examination, we have assumed (a) the authenticity of original documents and
the genuineness of all signatures, (b) the conformity to the originals of all
documents submitted to us as copies and (c) the truth, accuracy and completeness
of the information, representations and warranties contained in the records,
documents, instruments and certificates we have reviewed.

      We are of the opinion that the Notes have been duly authorized and that
when the Notes, in the form included in the Indenture, have been duly completed,
executed, authenticated and delivered in accordance with the Indenture and sold
and delivered as described in the Registration Statement and its related
prospectus, the Notes will be valid and binding obligations of the Company
entitled to the benefits of the Indenture. We are of the further opinion that
the Conversion Shares have been duly authorized and, when issued by the Company
upon conversion of the Notes in accordance with the Indenture, will be validly
issued, fully paid and nonassessable.


      We express no opinion as to (i) the effect of any bankruptcy, insolvency,
reorganization, arrangement, fraudulent conveyance, moratorium or other similar
laws relating to or affecting the rights of creditors generally, including,
without limitation, laws relating to fraudulent transfers or conveyances and
preferences, (ii) rights to indemnification and contribution contained in the
Notes, the Indenture and the Registration Rights Agreement dated as of May 16,
2003 between the Company and the initial purchasers named therein, which may be
limited by applicable law or equitable principles, or (iii) the




effect of general principles of equity, including without limitation, concepts
of materiality, reasonableness, good faith and fair dealing, and the possible
unavailability of specific performance, injunctive relief or other equitable
relief, and limitations on rights of acceleration regardless of whether
considered in a proceeding in equity or at law.

      We hereby consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement and to the use of our name under the caption "Legal
Matters" in the Registration Statement and the Prospectus included therein.

                                      Sincerely,

                                      WILSON SONSINI GOODRICH & ROSATI
                                      Professional Corporation

                                      /s/ Wilson Sonsini Goodrich & Rosati, P.C.