SAN JOSE, Calif., May 24, 2006--KLA-Tencor Corporation (NASDAQ: KLAC) today announced that its Board of Directors has appointed a special committee of independent directors to conduct an internal investigation relating to past stock options granted to employees during the 1995 to 2001 timeframe. The special committee is investigating the timing of such grants and related accounting and documentation and will be assisted by outside legal counsel and accounting experts.

KLA-Tencor also said that it has received subpoenas from the U.S. Attorney's Offices for the Eastern District of New York and Northern District of California requesting information relating to its past stock option grants. KLA-Tencor said that it will cooperate fully with any government or regulatory investigation into these matters. KLA-Tencor further disclosed that on May 22, 2006, it was served with a complaint relating to a lawsuit filed in the United States District Court for the Northern District of California filed by the Theodore R. Kornreich Revocable Trust, derivatively on behalf of KLA-Tencor.

About KLA-Tencor: KLA-Tencor is the world leader in yield management and process control solutions for semiconductor manufacturing and related industries. Headquartered in San Jose, Calif., the company has sales and service offices around the world. An S&P 500 company, KLA-Tencor is traded on the Nasdaq National Market under the symbol KLAC. Additional information about the company is available on the Internet at http://www.kla-tencor.com

Contact:
Meggan Powers
Director Corporate Communications