<PAGE>
   AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON DECEMBER 4, 2001
                                                  REGISTRATION NO. 333-_________

================================================================================


                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                                  ------------

                            LAM RESEARCH CORPORATION
             (Exact Name of Registrant as Specified in Its Charter)

                  DELAWARE                                 94-2634797
      (State or other jurisdiction of                   (I.R.S. Employer
       incorporation or organization)                  Identification No.)

              4650 CUSHING PARKWAY, FREMONT, CALIFORNIA 94538-6470
                    (Address of principal executive offices)

                                MERCEDES JOHNSON
               VICE PRESIDENT, FINANCE AND CHIEF FINANCIAL OFFICER
                            LAM RESEARCH CORPORATION
                              4650 CUSHING PARKWAY,
                         FREMONT, CALIFORNIA 94538-6470
                                 (510) 659-0200
            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)

                                  ------------

                                   Copies to:

                            TIMOTHY G. HOXIE, ESQUIRE
                       HELLER EHRMAN WHITE & MCAULIFFE LLP
                                 333 BUSH STREET
                         SAN FRANCISCO, CALIFORNIA 94104
                            TELEPHONE: (415) 772-6000
                            FACSIMILE: (415) 772-6268

                       1999 STOCK OPTION PLAN, AS AMENDED

<TABLE>
<CAPTION>
                                  CALCULATION OF REGISTRATION FEE
======================================================================================================
                                                    PROPOSED        PROPOSED
                                                    MAXIMUM         MAXIMUM
      TITLE OF SECURITIES         AMOUNT TO BE   OFFERING PRICE     AGGREGATE           AMOUNT OF
       TO BE REGISTERED           REGISTERED(1)   PER SHARE(2)   OFFERING PRICE(2)  REGISTRATION FEE
------------------------------------------------------------------------------------------------------
<S>                                <C>               <C>            <C>                 <C>
Common Stock, $0.001 par value     12,500,000        $21.99         $274,875,000        $65,695.13
======================================================================================================
</TABLE>

(1)  Pursuant to Rule 416(a), this registration statement also covers any
     additional securities that may be offered or issued in connection with any
     stock split, stock dividend or similar transaction.

(2)  Estimated solely for the purpose of computing the amount of the
     registration fee pursuant to Rule 457(c) under the Securities Act of 1933,
     as amended, based on the average of the high and low prices of the
     Registrant's Common Stock reported on the Nasdaq National Market on
     December 3, 2001.

                                  ------------


================================================================================

<PAGE>

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

        The following documents, which have been filed by Lam Research
Corporation (the "Registrant") with the Securities and Exchange Commission (the
"Commission"), are hereby incorporated by reference in this Registration
Statement:

        (a)    Registrant's Annual Report on Forms 10-K for the fiscal year
               ended June 24, 2001;

        (b)    Registrant's Current Report on Form 8-K filed on July 25, 2001;

        (c)    Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
               ended September 23, 2001;

        (d)    The description of Registrant's Common Stock as set forth in the
               Registrant's Registration Statement filed with the Commission on
               Form 8-B on April 11, 1990 and any amendment or report filed for
               the purpose of updating such description; and

        (e)    The description of Registrant's Rights Agreement and Preferred
               Stock Purchase Rights as set forth in Registrant's Registration
               Statements on Forms 8-A and 8-A/A filed on January 28, 1997 and
               January 30 1997.

        All documents subsequently filed by the Company pursuant to Sections
13(a), 13(c), 14 or 15(d) of the Exchange Act, prior to the filing of a
post-effective amendment to this Registration Statement which indicates that all
securities offered hereby have been sold or which deregisters all securities
remaining unsold, shall be deemed to be incorporated by reference in this
Registration Statement and to be a part hereof from the date of filing of such
documents.

ITEM 4.  DESCRIPTION OF  SECURITIES

         Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL

         Not applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

        Section 102 of the Delaware General Corporation Law allows a corporation
to eliminate the personal liability of directors of a corporation to the
corporation or to any of its stockholders for monetary damage for a breach of
his or her fiduciary duty as a director, except in the case where the director
breached his or her duty of loyalty, failed to act in good faith, engaged in
intentional misconduct or knowingly violated a law, authorized the payment of a
dividend or approved a stock repurchase in violation of Delaware corporate law
or obtained an improper personal benefit. The Registrant's Certificate of
Incorporation contains a provision that eliminates directors' personal liability
as set forth above.

        Section 145 of the Delaware General Corporation Law, as amended,
provides that a corporation may indemnify any person who was or is a party or is
threatened to be made a party to any threatened, pending or completed action,
suit or proceeding, whether civil, criminal, administrative or investigative, by
reason of the fact that he or she is or was a director, officer, employee or
agent of the corporation or is or was serving at its request in such capacity in
another corporation or business association against expenses (including
attorneys' fees), judgments, fines and amounts paid in settlement actually and
reasonably incurred by him or her in connection with such action, suit or
proceeding if he or she acted in good faith and in a manner he or she reasonably
believed to be in or not opposed to the best interests of the corporation and,
with respect to any criminal action or proceeding, had no reasonable cause to
believe his or her conduct was unlawful.

        The Registrant's Certificate of Incorporation provides that, to the
fullest extent permitted by the Delaware General Corporation Law, no director of
the Company shall be personally liable to the Company or its stockholders for
monetary damages for breach of fiduciary duty as a director. The Certificate of
Incorporation also provides that no amendment or repeal of such provision or
adoption of an inconsistent provision shall apply to or have any effect on the
protection from personal liability to the Company or its stockholders permitted
thereunder with respect to any matter occurring, or any cause of action, suit or
claim that, but for the Certificate of Incorporation, would accrue or arise
prior to such amendment, repeal or adoption of an inconsistent provision.
Additionally, the Registrant's Amended and Restated Bylaws provide that the
Registrant will indemnify to the maximum extent authorized by law each of its
directors and officers against expenses incurred in connection with any
proceeding arising by reason of the fact that such person is or was an agent of
the corporation.

        The Registrant has entered into indemnification agreements with its
directors and certain of its officers. The Registrant has also obtained on
behalf of its officers and directors insurance against losses arising from any
claim asserted against or incurred by such individual in any such capacity,
subject to certain exclusions.

        See also the undertakings set out in response to Item 9.




                                      II-1
<PAGE>

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not applicable.

ITEM 8.  EXHIBITS

<TABLE>
<CAPTION>
      Item
       No.                             Description of Item
      ------   -----------------------------------------------------------------
      <S>      <C>
        4.1    Lam Research Corporation 1999 Stock Incentive Plan, as amended

        5.1    Opinion of Heller Ehrman White & McAuliffe LLP

        23.1   Consent of Independent Auditors

        23.2   Consent of Heller Ehrman White & McAuliffe LLP (filed as part of
               Exhibit 5.1)

        24.1   Power of Attorney (See page II-3)
</TABLE>



ITEM 9.  UNDERTAKINGS

        A. The undersigned registrant hereby undertakes:

           (1) To file, during any period in which offers or sales are being
made, a post-effective amendment to this registration statement;

               (i) To include any prospectus required by Section 10(a)(3) of the
Securities Act of 1933;

               (ii) To reflect in the prospectus any facts or events arising
after the effective date of the registration statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in the registration
statement; and

               (iii) To include any material information with respect to the
plan of distribution not previously disclosed in the registration statement or
any material change to such information in the registration statement; provided,
however, that paragraphs A(1)(i) and A(1)(ii) do not apply if the information
required to be included in a post-effective amendment by those paragraphs is
contained in periodic reports filed by the registrant pursuant to Section 13 or
15(d) of the Securities Exchange Act of 1934 that are incorporated by reference
in the registration statement.

           (2) That, for the purpose of determining any liability under the
Securities Act of 1933, each such post-effective amendment shall be deemed to be
a new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

           (3) To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

        B. The undersigned registrant hereby undertakes that, for purposes of
determining liability under the Securities Act of 1933, each filing of the
registrant's annual report pursuant to Section 13(a) or 15(d) of the Securities
Exchange Act of 1934 that is incorporated by reference in the registration
statement shall be deemed a new registration statement relating to the
securities offered therein, and the offering of such securities at that time
shall be deemed to be the initial bona fide offering thereof.

        C. Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons
of the registrant pursuant to the foregoing provisions, or otherwise, the
registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Securities Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
registrant of expenses incurred or paid by a director, officer or controlling
person of the registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the Securities
Act and will be governed by the final adjudication of such issue.




                                      II-2
<PAGE>

                                   SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the city of Fremont, State of California, on this 4th day of
December, 2001.


                                                   LAM RESEARCH CORPORATION


                                                   By: /s/ Mercedes Johnson
                                                      --------------------------
                                                   Mercedes Johnson
                                                   Vice President, Finance and
                                                   Chief Financial Officer

                       POWER OF ATTORNEY TO SIGN AMENDMENT

        KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears
below does hereby constitute and appoint Mercedes Johnson and Mark Frey, and
each of them, with full power of substitution, such person's true and lawful
attorneys-in-fact and agents for such person in such person's name, place and
stead, in any and all capacities, to sign any or all amendments (including
post-effective amendments) to this Registration Statement on Form S-8 and to
file the same, with all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting unto said
attorneys-in-fact and agents full power and authority to do and perform each and
every act and thing requisite and necessary to be done in and about the premises
in order to effectuate the same as fully, to all intents and purposes, as he or
such person might or could do in person, hereby ratifying and confirming all
that said attorneys-in-fact and agents may lawfully do or cause to be done by
virtue hereof.

        Pursuant to the requirements of the Securities Act, this Registration
Statement on Form S-8 has been signed by the following persons in the capacities
and on the dates indicated.

<TABLE>
<CAPTION>
          Signature                               Capacity                         Date
-------------------------------     -------------------------------------    ----------------
<S>                                 <C>                                      <C>

/s/ James W. Bagley                 Chairman, Chief Executive Officer        December 4, 2001
-----------------------------       and Director
James W. Bagley

/s/ Mercedes Johnson                Vice President, Finance and Chief        December 4, 2001
-----------------------------       Financial Officer (Principal
Mercedes Johnson                    Financial Officer)

/s/ Mark S. Frey                    Corporate Controller (Principal          December 4, 2001
-----------------------------       Accounting Officer)
Mark S. Frey

/s/ David G. Arscott                Director                                 December 4, 2001
-----------------------------
David G. Arscott

/s/ Robert Berdahl                  Director                                 December 4, 2001
-----------------------------
Robert Berdahl

/s/ Richard J. Elkus, Jr.           Director                                 December 4, 2001
-----------------------------
Richard J. Elkus, Jr.

/s/ Jack R. Harris                  Director                                 December 4, 2001
-----------------------------
Jack R. Harris

/s/ Grant M. Inman                  Director                                 December 4, 2001
-----------------------------
Grant M. Inman

/s/ Kenneth M. Thompson             Director                                 December 4, 2001
-----------------------------
Kenneth M. Thompson
</TABLE>




                                      II-3
<PAGE>

Index to Exhibits



<TABLE>
<CAPTION>
Item
 No.                             Description of Item
------   -----------------------------------------------------------------
<S>      <C>
  4.1    Lam Research Corporation 1999 Stock Incentive Plan, as amended

  5.1    Opinion of Heller Ehrman White & McAuliffe LLP

  23.1   Consent of Independent Auditors

  23.2   Consent of Heller Ehrman White & McAuliffe LLP (filed as part of
         Exhibit 5.1)

  24.1   Power of Attorney (See page II-3)
</TABLE>





                                      II-4

