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EXHIBIT 21.  LIST OF SUBSIDIARIES

- -    MKS International, Inc.

- -    MKS Instruments Deutschland GmbH

- -    MKS Instruments France S.A.

- -    MKS Instruments Canada Ltd.

- -    MKS Instruments, U.K. Limited

- -    MKS East, Inc.

- -    MKS Japan, Inc.

- -    MKS Korea Co., Ltd.

- -    MKS FSC, Inc.

- -    MKS MSC, Inc.



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