EXHIBIT 23.1

                       CONSENT OF INDEPENDENT ACCOUNTANTS

We hereby consent to the incorporation by reference in the Registration
Statements on Form S-8 (No. 333-78069, 333-78071, 333-78073, 333-31224,
333-54486, 333-54488 and 333-54490) and Form S-3 (No. 333-34450) of MKS
Instruments, Inc. of our report dated January 26, 2001 relating to the
consolidated financial statements and the consolidated financial statement
schedule of MKS Instruments, Inc. as of December 31, 2000 and 1999 and for the
years ended December 31, 2000, 1999 and 1998, which appears in this Current
Report on Form 8-K dated November 27, 2001.

/s/ PricewaterhouseCoopers LLP

Boston, Massachusetts
November 27, 2001