CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration
Statement on Form S-8 of our report dated March 14, 2005 relating to the
financial statements, financial statement schedule, management's assessment of
the effectiveness of internal control over financial reporting and the
effectiveness of internal control over financial reporting, of MKS Instruments,
Inc., which appears in MKS Instruments, Inc.'s Annual Report on Form 10-K for
the year ended December 31, 2004.

/s/ PricewaterhouseCoopers LLP

Boston, Massachusetts
August 2, 2005