FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number: 3235-0287
Estimated average burden hours per response... 0.5

(Print or Type Responses)
1. Name and Address of Reporting Person *
LAMB MAUREEN L
   2. Issuer Name and Ticker or Trading Symbol
KLA TENCOR CORP [KLAC] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
VP Finance & Treasury
(Last)
(First)
(Middle)
C/O KLA-TENCOR CORPORATION, 160 RIO ROBLES		 3. Date of Earliest Transaction (Month/Day/Year)
05/26/2005
(Street)

SAN JOSE, CA 95130		 4. If Amendment, Date Original Filed(Month/Day/Year)
 6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)		 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)		 4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)		 5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)		 6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)		 7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 05/26/2005   M   334 A $ 33.75 4,510 D  
Common Stock 05/26/2005   S   334 D $ 45 4,176 D  
Common Stock 05/26/2005   M   750 A $ 26.25 4,926 D  
Common Stock 05/26/2005   S   750 D $ 45 4,176 D  
Common Stock 05/26/2005   M   625 A $ 32.75 4,801 D  
Common Stock 05/26/2005   S   625 D $ 45.02 4,176 D  
Common Stock 05/26/2005   M   1,875 A $ 29.31 6,051 D  
Common Stock 05/26/2005   S   1,875 D $ 45 4,176 D  
Common Stock 05/26/2005   M   1,875 A $ 37.05 6,051 D  
Common Stock 05/26/2005   S   1,875 D $ 45 4,176 D  
Common Stock 05/26/2005   M   2,250 A $ 34.67 6,426 D  
Common Stock 05/26/2005   S   2,250 D $ 45.0517 4,176 D  

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number. SEC 1474 (9-02)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)		 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)		 5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)		 6. Date Exercisable and Expiration Date
(Month/Day/Year)		 7. Title and Amount of Underlying Securities
(Instr. 3 and 4)		 8. Price of Derivative Security
(Instr. 5)		 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)		 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)		 11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Non-Qualified Stock Option (right to buy) $ 26.25 05/26/2005   M     750 11/10/2001 11/10/2010 Common Stock 750 $ 45 750 D  
Non-Qualified Stock Option (right to buy) $ 29.31 05/26/2005   M     1,875 10/02/2002 10/02/2011 Common Stock 1,875 $ 45 6,375 D  
Non-Qualified Stock Option (right to buy) $ 32.75 05/26/2005   M     625 04/04/2002 04/04/2011 Common Stock 625 $ 45.02 1,375 D  
Non-Qualified Stock Option (right to buy) $ 33.75 05/26/2005   M     334 10/27/2000 10/27/2009 Common Stock 334 $ 45 0 D  
Non-Qualified Stock Option (right to buy) $ 34.67 05/26/2005   M     2,250 11/08/2003 01/28/2013 Common Stock 2,250 $ 45.0517 3,750 D  
Non-Qualified Stock Option (right to buy) $ 37.05 05/26/2005   M     1,875 11/08/2003 11/08/2012 Common Stock 1,875 $ 45 1,875 D  
Non-Qualified Stock Option (right to buy) $ 40.66             10/27/2004 08/02/2014 Common Stock 2,250   2,250 D  
Non-Qualified Stock Option (right to buy) $ 41.79             09/21/2005 09/21/2014 Common Stock 15,000   15,000 D  
Non-Qualified Stock Option (right to buy) $ 44.6875             08/13/2001 08/13/2010 Common Stock 15,000   15,000 D  
Non-Qualified Stock Option (right to buy) $ 45.16             10/27/2004 04/26/2014 Common Stock 3,750   3,750 D  
Non-Qualified Stock Option (right to buy) $ 51.229             11/08/2003 07/30/2013 Common Stock 3,750   3,750 D  
Non-Qualified Stock Option (right to buy) $ 53.86             10/27/2004 10/27/2013 Common Stock 6,000   6,000 D  
Non-Qualified Stock Option (right to buy) $ 58.10             10/27/2004 01/27/2014 Common Stock 3,000   3,000 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
LAMB MAUREEN L
C/O KLA-TENCOR CORPORATION
160 RIO ROBLES
SAN JOSE, CA 95130		       VP Finance & Treasury  

Signatures

 By: Stuart J. Nichols For: Maureen Lamb   05/27/2005
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.