UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              Washington, DC 20549


                                    Form 8-K


                                 Current Report

     Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934


        Date of Report (Date of earliest event reported): April 21, 2004


                             KLA-Tencor Corporation
             (Exact name of registrant as specified in its charter)


                                    000-09992
                            (Commission File Number)


                   Delaware                                 04-2564110
---------------------------------------------          -------------------
(State or other jurisdiction of incorporation)          (I.R.S. Employer
                                                       Identification No.)


                                 160 Rio Robles
                              San Jose, California
                                      95134
             (Address of principal executive offices, with zip code)


                                 (408) 875-3000
              (Registrant's telephone number, including area code)


                                       N/A
          (Former name or former address, if changed since last report)





Item 7.    Financial Statements and Exhibits.

     (c) Exhibits.

Exhibit    Description
-------    -----------
  99.1     Press Release issued by KLA-Tencor Corporation dated April 21, 2004.


Item 12.    Results of Operations and Financial Condition

       On April 21, 2004, KLA-Tencor Corporation, (the "Company") issued a press
release regarding its financial results for the quarter ended March 31, 2004. A
copy of the press release is furnished as Exhibit 99.1 to this Form 8-K.

       The information in this Form 8-K and the exhibit attached hereto shall
not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act
of 1934, as amended (the "Exchange Act"), or otherwise subject to the
liabilities under that section, nor shall it be deemed incorporated by reference
in any filing under the Securities Act of 1933, as amended, or the Exchange Act,
regardless of any general incorporation language in such filing.


                                       -2-



                                   SIGNATURES

      Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                                   KLA-TENCOR CORPORATION


Date:  April 21, 2004                              By:  /s/  John H. Kispert
                                                      ------------------------
                                                          John H. Kispert
                                                      Executive Vice President
                                                     and Chief Financial Officer




INDEX TO EXHIBITS

Exhibit    Description
-------    -----------
  99.1     Press Release issued by KLA-Tencor Corporation dated April 21, 2004.