Exhibit 21.1 KLA-Tencor Subsidiaries State or Other Jurisdiction of Name Incorporation DOMESTIC SUBSIDIARIES International Sales & Business, Inc. California KLA-Tencor Building Corporation California KLA-Tencor DISC Corporation California KLA-Tencor International Corporation California KLA-Tencor Klinnik Corporation California KLA-Tencor Technologies Corporation California KLA-Tencor China Corporation California KLA-Tencor Asia-Pac Distribution Corporation California VLSI Standards, Inc. California INTERNATIONAL SUBSIDIARIES KLA-Tencor (Cayman) Limited I Cayman Islands KLA-Tencor (Cayman) Limited II Cayman Islands KLA-Tencor (Cayman) Limited III Cayman Islands KLA-Tencor (Cayman) Limited IV Cayman Islands KLA-Tencor (Israel) Corporation Israel KLA-Tencor Holding Corporation 1987 Limited Israel KLA-Tencor Corporation 1992 Limited Israel KLA-Tencor Integrated Metrology (Israel) (2002) Ltd. Israel KLA-Tencor Italy S.R.L. Italy KLA-Tencor Japan, Ltd. Japan VLSI Standards, KK Japan KLA-Tencor GmbH Germany KLA-Tencor France SARL France KLA-Tencor Korea, Inc. Korea KLA-Tencor Limited United Kingdom KLA-Tencor (Service) Limited United Kingdom KLA-Tencor (Malaysia) Sdn Bhd Malaysia KLA-Tencor (Singapore) PTE, Ltd. Singapore KLA-Tencor International Trading (Shanghai) Co. Ltd. China KLA-Tencor Microelectronics Equipment (Tianjin) Co., LTD China KLA Instruments, S.A. Switzerland Yield Analysis Software Technologies, Ins. Taiwan Lee Ta Technologies (BVI), Inc. British Virgin Islands KLA-Tencor (Thailand), Ltd. Thailand