<PAGE>   1
     As filed with the Securities and Exchange Commission on July 31, 1997
                                                       Registration No. 333-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

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

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

                             KLA-TENCOR CORPORATION
             (Exact name of registrant as specified in its charter)

          DELAWARE                                     04-2564110
          --------                                     ----------
   (State of incorporation)                (I.R.S. Employer Identification No.)

                                 160 RIO ROBLES
                               SAN JOSE, CA 95134
          (Address, including zip code, of principal executive offices)

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

                             1982 STOCK OPTION PLAN
                           (Full Titles of the Plans)

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

                                  LISA C. BERRY
                         VICE PRESIDENT, GENERAL COUNSEL
                           KLA INSTRUMENTS CORPORATION
                                 160 Rio Robles
                               San Jose, CA 95134
                     (Name and address of agent for service)
                                
                                 (408) 468-4200
                     (Telephone number, including area code,
                              of agent for service)

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

                                    Copy to:
                             JUDITH M. O'BRIEN, ESQ.
                       WILSON, SONSINI, GOODRICH & ROSATI
                            Professional Corporation
                               650 Page Mill Road
                           Palo Alto, California 94304


<TABLE>
<CAPTION>
================================================================================================================================
                                                         CALCULATION OF REGISTRATION FEE
================================================================================================================================
                                                         Proposed Maximum          Proposed Maximum
  Title of Securities to              Amount to be      Offering Price Per        Aggregate offering      Amount of Registration
       be Registered                  Registered              Share(1)                 Price(1)                    Fee
--------------------------------------------------------------------------------------------------------------------------------
 <S>                                   <C>                   <C>                     <C>                     <C>
 Common Stock, $.001 par               2,501,603             $61.7188                $154,395,935                 $46,787
 value, to be issued
 upon exercise of
 options granted under
 the Amended 1982 Stock
 Option Plan

          Total                        2,501,603             $61.7188                $154,395,935                 $46,787
 ==============================================================================================================================
</TABLE>


________________________

       (1) The Proposed Maximum Offering Price Per Share was estimated pursuant
to Rule 457(h) under the Securities Act of 1933, as amended (the "SECURITIES
ACT") solely for the purpose of calculating the registration fee, based on the
average between the high and low price of the Registrant's stock as reported in
the Nasdaq National Market on July 29, 1997.




<PAGE>   2
                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

         KLA-Tencor Corporation (the "REGISTRANT" or the "COMPANY") hereby
incorporates by reference in this registration statement the following
documents:

         (a)     The Registrant's Annual Report on Form 10-K for the fiscal
                 year ended June 30, 1996 (File No. 000-09992) pursuant to
                 Section 13(a) of the Securities Exchange Act of 1934, as
                 amended (the "Exchange Act").

         (b)     All other reports filed pursuant to Section 13(a) or 15(d) of
                 the Exchange Act since the end of the latest fiscal year
                 covered by the document referred to in (a) above.

         (c)     The description of the Registrant's Common Stock as set forth
                 in the Registration Statement filed by the Registrant on Form
                 8-A on March 29, 1989 (File No. 000-09992) pursuant to Section
                 12(g) of the Exchange Act and any amendments or reports
                 thereto filed with the Securities and Exchange Commission for
                 the purpose of updating such description including Amendment
                 No. 1 to Form 8-A filed September 25, 1995 and Amendment No. 2
                 to Form 8-A filed September 24, 1996.

         All documents subsequently filed by the Registrant pursuant to Sections
13(a), 13(c), 14 and 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.

         The class of securities to be offered is registered under Section 12
of the Exchange Act.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

         Inapplicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

         Section 145(a) of the Delaware General Corporation Law (the "DGCL")
provides in relevant part 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 (other than an action by or in the right of the
corporation) by reason of the fact that he is or was a director, officer,
employee or agent of the corporation, or is or was serving at the request of
the corporation as a director, officer, employee or agent of another
corporation, partnership, joint venture, trust or other enterprise, against
expenses (including attorneys' fees), judgments, fines and amounts paid in
settlement actually and reasonably incurred by him in connection with such
action, suit or proceeding if he acted in good faith and in a manner he
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 conduct was unlawful."  With respect to
derivative actions, Section 145(b) of the DGCL provides in relevant part that
"[a] corporation may indemnify any person who was or is a party or is
threatened to be made a party to any





                                      II-1
<PAGE>   3

threatened, pending or completed action or suit by or in the right of the
corporation to procure a judgment in its favor...[by reason of his service in
one of the capacities specified in the preceding sentence] against expenses
(including attorneys' fees) actually and reasonably incurred by him in
connection with the defense or settlement of such action or suit if he acted in
good faith and in a manner he reasonably believed to be in or not opposed to
the best interests of the corporation and except that no indemnification shall
be made in respect of any claim, issue or matter as to which such person shall
have been adjudged to be liable to the corporation unless and only to the
extent that the Court of Chancery or the court in which such action or suit was
brought shall determine upon application that, despite the adjudication of
liability but in view of all the circumstances of the case, such person is
fairly and reasonably entitled to indemnity for such expenses which the Court
of Chancery or such other court shall deem proper."

         The Company's Amended and Restated Certificate of Incorporation
provides that to the fullest extent permitted by the DGCL, 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 Amended and
Restated Certificate of Incorporation also provides that no amendment or repeal
of such provision shall apply to or have any effect on the right to
indemnification permitted thereunder with respect to claims arising from acts
or omissions occurring in whole or in part before the effective date of such
amendment or repeal whether asserted before or after such amendment or repeal.

         The Company's Bylaws provide that the Company shall indemnify to the
full extent permitted by the DGCL each of its directors, officers, employees
and other agents against expenses actually and reasonably incurred in
connection with any proceeding arising by reason of the fact that such person
is or was an agent of the Company.

         The Company has entered into indemnification agreements with its
directors and executive officers and intends to enter into indemnification
agreements with any new directors and executive officers in the future.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Inapplicable.

ITEM 8.  EXHIBITS

         See Exhibit Index.

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 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.

                 (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.





                                      II-2
<PAGE>   4

         (b)     The undersigned registrant hereby undertakes that, for
purposes of determining any liability under the Securities Act of 1933, each
filing of the registrant's annual report pursuant to Section 13(a) or Section
15(d) of the Securities Exchange Act of 1934 (and, where applicable, each
filing of an employee benefit plan's annual report pursuant to Section 15(d) of
the Securities Exchange Act of 1934) that is incorporated by reference in the
registration statement 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.

         (c)     Insofar as indemnification for liabilities arising under the
Securities Act of 1933 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 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 Act and
will be governed by the final adjudication of such issue.




















                                      II-3
<PAGE>   5
                                   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 Milpitas, State of California, on July 31,
1997.


                                            KLA-TENCOR CORPORATION


                                            By:  /s/ LISA C. BERRY
                                                 -----------------------------
                                                 Lisa C. Berry,
                                                 Vice President and
                                                 General Counsel





















                                      II-4
<PAGE>   6
                               POWER OF ATTORNEY

         KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Kenneth Levy and Lisa C. Berry, and
each of them, their true and lawful attorneys and agents, with full power of
substitution, each with power to act alone, to sign and execute on behalf of
the undersigned any amendment or amendments to this Registration Statement on
Form S-8 and to perform any acts necessary in order to file such amendments,
and each of the undersigned does hereby ratify and confirm all that said
attorneys and agents, or their or his or her substitutes, shall do or cause to
be done by virtue hereof.  Pursuant to the requirements of the Securities Act
of 1933, as amended, this Registration Statement has been signed by the
following persons in the capacities and on the dates indicated.

<TABLE>
<CAPTION>
             Signature                                    Title                        Date
             ---------                                    -----                        ----
 <S>                                           <C>                                 <C>
/s/ Kenneth Levy                              Chairman of the Board and           July 31, 1997
--------------------------------              Director
Kenneth Levy                                
                                                       

/s/ Jon D. Tompkins                           Chief Executive Officer and         July 31, 1997
--------------------------------              Director
Jon D. Tompkins                               (Principal Executive Officer)
                                                       
                                                                           
/s/ Kenneth L. Schroeder                      President, Chief Operating          July 31, 1997
--------------------------------              Officer and Director
Kenneth L. Schroeder                        


/s/ Robert J. Boehlke                         Vice President, Administration      July 31, 1997
--------------------------------              and Finance, and Chief Financial
Robert J. Boehlke                             Officer (Principal Financial and
                                              Accounting Officer)

/s/ James W. Bagley                           Director                            July 31, 1997
--------------------------------  
James W. Bagley

/s/ Edward W. Barnholt                        Director                            July 31, 1997
--------------------------------  
Edward W. Barnholt

/s/ Leo J. Chamberlain                        Director                            July 31, 1997
--------------------------------  
Leo J. Chamberlain

/s/ Richard J. Elkus, Jr.                     Director                            July 31, 1997
--------------------------------  
Richard J. Elkus, Jr.

/s/ Dean O. Morton                            Director                            July 31, 1997
--------------------------------  
Dean O. Morton

/s/ Yoshio Nishi                              Director                            July 31, 1997
--------------------------------  
Yoshio Nishi

/s/ Samuel Rubinovitz                         Director                            July 31, 1997
--------------------------------  
Samuel Rubinovitz

/s/ Dag Tellefsen                             Director                            July 31, 1997
--------------------------------  
Dag Tellefsen

/s/ Lida Urbanek                              Director                            July 31, 1997
--------------------------------  
Lida Urbanek
</TABLE>





                                      II-5
<PAGE>   7
                          KLA INSTRUMENTS CORPORATION

                       REGISTRATION STATEMENT ON FORM S-8

                               INDEX TO EXHIBITS


 Exhibit
  Number                                 Description
------------              -------------------------------------------------

     4.1*                 Certificate of Incorporation, as amended.

     4.2**                Bylaws of the Registrant, as amended.

     4.3***               Amended and Restated Rights Agreement dated as of
                          August 30, 1995 between the Registrant and The First
                          National Bank of Boston, as Rights Agent.

     5.1                  Opinion re: legality

     10.74+               Restated 1982 Stock Option Plan, as amended on
                          November 18, 1996.

     23.1                 Consent of Counsel (included in Exhibit 5.1)

     23.2                 Consent of Independent Accountants

     24.1                 Power of Attorney (see Page II-5)

_______________________________

         *       Incorporated by reference to Exhibit 3.1 to the Registrant's
                 Registration Statement on Form S-4, dated March 11, 1997
                 (Commission File No. 333-23075).

         **      Incorporated by reference to Exhibit 4.2 to the Registrant's
                 Registration Statement on Form S-8, dated May 8, 1997
                 (Commission File No. 333-26681).

         ***     Incorporated by reference to the Registrant's report on Form
                 8-A/A Amendment No. 1 to the Registration Statement on Form
                 8-A (filed September 24, 1996, Commission File No. 000-9992).

         +       Incorporated by reference to Exhibit  10.74 to the
                 Registrant's Registration Statement on Form S-8, dated March
                 7, 1997.  (Commission File No. 333-22941)















                                      II-6
[{"type": "S-8", "sequence": "1", "description": "FORM S-8 DATED JULY 31, 1997", "secsgml_size_bytes": 19567}]
{"company-data": {"conformed-name": "KLA TENCOR CORP", "cik": "0000319201", "assigned-sic": "3827", "irs-number": "042564110", "state-of-incorporation": "DE", "fiscal-year-end": "0630"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-32537", "film-number": "97649099"}, "business-address": {"street1": "160 RIO ROBLES", "city": "SAN JOSE", "state": "CA", "zip": "95134", "phone": "4084344200"}, "mail-address": {"street1": "160 RIO ROBLES", "city": "SAN JOSE", "state": "CA", "zip": "95161-9055"}, "former-company": {"former-conformed-name": "KLA INSTRUMENTS CORP", "date-changed": "19920703"}}
1
     As filed with the Securities and Exchange Commission on July 31, 1997
                                                       Registration No. 333-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

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

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

                             KLA-TENCOR CORPORATION
             (Exact name of registrant as specified in its charter)

          DELAWARE                                     04-2564110
          --------                                     ----------
   (State of incorporation)                (I.R.S. Employer Identification No.)

                                 160 RIO ROBLES
                               SAN JOSE, CA 95134
          (Address, including zip code, of principal executive offices)

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

                             1982 STOCK OPTION PLAN
                           (Full Titles of the Plans)

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

                                  LISA C. BERRY
                         VICE PRESIDENT, GENERAL COUNSEL
                           KLA INSTRUMENTS CORPORATION
                                 160 Rio Robles
                               San Jose, CA 95134
                     (Name and address of agent for service)
                                
                                 (408) 468-4200
                     (Telephone number, including area code,
                              of agent for service)

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

                                    Copy to:
                             JUDITH M. O'BRIEN, ESQ.
                       WILSON, SONSINI, GOODRICH & ROSATI
                            Professional Corporation
                               650 Page Mill Road
                           Palo Alto, California 94304
================================================================================================================================
                                                         CALCULATION OF REGISTRATION FEE
================================================================================================================================
                                                         Proposed Maximum          Proposed Maximum
  Title of Securities to              Amount to be      Offering Price Per        Aggregate offering      Amount of Registration
       be Registered                  Registered              Share(1)                 Price(1)                    Fee
--------------------------------------------------------------------------------------------------------------------------------
Common Stock, $.001 par               2,501,603             $61.7188                $154,395,935                 $46,787
 value, to be issued
 upon exercise of
 options granted under
 the Amended 1982 Stock
 Option Plan

          Total                        2,501,603             $61.7188                $154,395,935                 $46,787
 ==============================================================================================================================
________________________

       (1) The Proposed Maximum Offering Price Per Share was estimated pursuant
to Rule 457(h) under the Securities Act of 1933, as amended (the "SECURITIES
ACT") solely for the purpose of calculating the registration fee, based on the
average between the high and low price of the Registrant's stock as reported in
the Nasdaq National Market on July 29, 1997.
2
                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

         KLA-Tencor Corporation (the "REGISTRANT" or the "COMPANY") hereby
incorporates by reference in this registration statement the following
documents:

         (a)     The Registrant's Annual Report on Form 10-K for the fiscal
                 year ended June 30, 1996 (File No. 000-09992) pursuant to
                 Section 13(a) of the Securities Exchange Act of 1934, as
                 amended (the "Exchange Act").

         (b)     All other reports filed pursuant to Section 13(a) or 15(d) of
                 the Exchange Act since the end of the latest fiscal year
                 covered by the document referred to in (a) above.

         (c)     The description of the Registrant's Common Stock as set forth
                 in the Registration Statement filed by the Registrant on Form
                 8-A on March 29, 1989 (File No. 000-09992) pursuant to Section
                 12(g) of the Exchange Act and any amendments or reports
                 thereto filed with the Securities and Exchange Commission for
                 the purpose of updating such description including Amendment
                 No. 1 to Form 8-A filed September 25, 1995 and Amendment No. 2
                 to Form 8-A filed September 24, 1996.

         All documents subsequently filed by the Registrant pursuant to Sections
13(a), 13(c), 14 and 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.

         The class of securities to be offered is registered under Section 12
of the Exchange Act.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

         Inapplicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

         Section 145(a) of the Delaware General Corporation Law (the "DGCL")
provides in relevant part 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 (other than an action by or in the right of the
corporation) by reason of the fact that he is or was a director, officer,
employee or agent of the corporation, or is or was serving at the request of
the corporation as a director, officer, employee or agent of another
corporation, partnership, joint venture, trust or other enterprise, against
expenses (including attorneys' fees), judgments, fines and amounts paid in
settlement actually and reasonably incurred by him in connection with such
action, suit or proceeding if he acted in good faith and in a manner he
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 conduct was unlawful."  With respect to
derivative actions, Section 145(b) of the DGCL provides in relevant part that
"[a] corporation may indemnify any person who was or is a party or is
threatened to be made a party to any

                                      II-1
3

threatened, pending or completed action or suit by or in the right of the
corporation to procure a judgment in its favor...[by reason of his service in
one of the capacities specified in the preceding sentence] against expenses
(including attorneys' fees) actually and reasonably incurred by him in
connection with the defense or settlement of such action or suit if he acted in
good faith and in a manner he reasonably believed to be in or not opposed to
the best interests of the corporation and except that no indemnification shall
be made in respect of any claim, issue or matter as to which such person shall
have been adjudged to be liable to the corporation unless and only to the
extent that the Court of Chancery or the court in which such action or suit was
brought shall determine upon application that, despite the adjudication of
liability but in view of all the circumstances of the case, such person is
fairly and reasonably entitled to indemnity for such expenses which the Court
of Chancery or such other court shall deem proper."

         The Company's Amended and Restated Certificate of Incorporation
provides that to the fullest extent permitted by the DGCL, 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 Amended and
Restated Certificate of Incorporation also provides that no amendment or repeal
of such provision shall apply to or have any effect on the right to
indemnification permitted thereunder with respect to claims arising from acts
or omissions occurring in whole or in part before the effective date of such
amendment or repeal whether asserted before or after such amendment or repeal.

         The Company's Bylaws provide that the Company shall indemnify to the
full extent permitted by the DGCL each of its directors, officers, employees
and other agents against expenses actually and reasonably incurred in
connection with any proceeding arising by reason of the fact that such person
is or was an agent of the Company.

         The Company has entered into indemnification agreements with its
directors and executive officers and intends to enter into indemnification
agreements with any new directors and executive officers in the future.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Inapplicable.

ITEM 8.  EXHIBITS

         See Exhibit Index.

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 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.

                 (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.

                                      II-2
4

         (b)     The undersigned registrant hereby undertakes that, for
purposes of determining any liability under the Securities Act of 1933, each
filing of the registrant's annual report pursuant to Section 13(a) or Section
15(d) of the Securities Exchange Act of 1934 (and, where applicable, each
filing of an employee benefit plan's annual report pursuant to Section 15(d) of
the Securities Exchange Act of 1934) that is incorporated by reference in the
registration statement 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.

         (c)     Insofar as indemnification for liabilities arising under the
Securities Act of 1933 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 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 Act and
will be governed by the final adjudication of such issue.

                                      II-3
5
                                   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 Milpitas, State of California, on July 31,
1997.

                                            KLA-TENCOR CORPORATION

                                            By:  /s/ LISA C. BERRY
                                                 -----------------------------
                                                 Lisa C. Berry,
                                                 Vice President and
                                                 General Counsel

                                      II-4
6
                               POWER OF ATTORNEY

         KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Kenneth Levy and Lisa C. Berry, and
each of them, their true and lawful attorneys and agents, with full power of
substitution, each with power to act alone, to sign and execute on behalf of
the undersigned any amendment or amendments to this Registration Statement on
Form S-8 and to perform any acts necessary in order to file such amendments,
and each of the undersigned does hereby ratify and confirm all that said
attorneys and agents, or their or his or her substitutes, shall do or cause to
be done by virtue hereof.  Pursuant to the requirements of the Securities Act
of 1933, as amended, this Registration Statement has been signed by the
following persons in the capacities and on the dates indicated.
Signature                                    Title                        Date
             ---------                                    -----                        ----
/s/ Kenneth Levy                              Chairman of the Board and           July 31, 1997
--------------------------------              Director
Kenneth Levy                                
                                                       

/s/ Jon D. Tompkins                           Chief Executive Officer and         July 31, 1997
--------------------------------              Director
Jon D. Tompkins                               (Principal Executive Officer)
                                                       
                                                                           
/s/ Kenneth L. Schroeder                      President, Chief Operating          July 31, 1997
--------------------------------              Officer and Director
Kenneth L. Schroeder                        

/s/ Robert J. Boehlke                         Vice President, Administration      July 31, 1997
--------------------------------              and Finance, and Chief Financial
Robert J. Boehlke                             Officer (Principal Financial and
                                              Accounting Officer)

/s/ James W. Bagley                           Director                            July 31, 1997
--------------------------------  
James W. Bagley

/s/ Edward W. Barnholt                        Director                            July 31, 1997
--------------------------------  
Edward W. Barnholt

/s/ Leo J. Chamberlain                        Director                            July 31, 1997
--------------------------------  
Leo J. Chamberlain

/s/ Richard J. Elkus, Jr.                     Director                            July 31, 1997
--------------------------------  
Richard J. Elkus, Jr.

/s/ Dean O. Morton                            Director                            July 31, 1997
--------------------------------  
Dean O. Morton

/s/ Yoshio Nishi                              Director                            July 31, 1997
--------------------------------  
Yoshio Nishi

/s/ Samuel Rubinovitz                         Director                            July 31, 1997
--------------------------------  
Samuel Rubinovitz

/s/ Dag Tellefsen                             Director                            July 31, 1997
--------------------------------  
Dag Tellefsen

/s/ Lida Urbanek                              Director                            July 31, 1997
--------------------------------  
Lida Urbanek
II-5
7
                          KLA INSTRUMENTS CORPORATION

                       REGISTRATION STATEMENT ON FORM S-8

                               INDEX TO EXHIBITS

 Exhibit
  Number                                 Description
------------              -------------------------------------------------

     4.1*                 Certificate of Incorporation, as amended.

     4.2**                Bylaws of the Registrant, as amended.

     4.3***               Amended and Restated Rights Agreement dated as of
                          August 30, 1995 between the Registrant and The First
                          National Bank of Boston, as Rights Agent.

     5.1                  Opinion re: legality

     10.74+               Restated 1982 Stock Option Plan, as amended on
                          November 18, 1996.

     23.1                 Consent of Counsel (included in Exhibit 5.1)

     23.2                 Consent of Independent Accountants

     24.1                 Power of Attorney (see Page II-5)

_______________________________

         *       Incorporated by reference to Exhibit 3.1 to the Registrant's
                 Registration Statement on Form S-4, dated March 11, 1997
                 (Commission File No. 333-23075).

         **      Incorporated by reference to Exhibit 4.2 to the Registrant's
                 Registration Statement on Form S-8, dated May 8, 1997
                 (Commission File No. 333-26681).

         ***     Incorporated by reference to the Registrant's report on Form
                 8-A/A Amendment No. 1 to the Registration Statement on Form
                 8-A (filed September 24, 1996, Commission File No. 000-9992).

         +       Incorporated by reference to Exhibit  10.74 to the
                 Registrant's Registration Statement on Form S-8, dated March
                 7, 1997.  (Commission File No. 333-22941)

                                      II-6