SEC FORM 3 SEC Form 3
FORM 3 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
 
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1. Name and Address of Reporting Person*
Eyerman Paul

(Last) (First) (Middle)
C/O 2 TECH DRIVE, SUITE 201

(Street)
ANDOVER MA 01810

(City) (State) (Zip)
2. Date of Event Requiring Statement (Month/Day/Year)
05/03/2010
3. Issuer Name and Ticker or Trading Symbol
MKS INSTRUMENTS INC [ MKSI ]
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
Director 10% Owner
X Officer (give title below) Other (specify below)
VP & GM, ENI and Medical
5. If Amendment, Date of Original Filed (Month/Day/Year)
6. Individual or Joint/Group Filing (Check Applicable Line)
X Form filed by One Reporting Person
Form filed by More than One Reporting Person
Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock 100 D
Table II - Derivative Securities Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4) 2. Date Exercisable and Expiration Date (Month/Day/Year) 3. Title and Amount of Securities Underlying Derivative Security (Instr. 4) 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 6. Nature of Indirect Beneficial Ownership (Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Restricted Stock Unit (1) (1) Common Stock 2,647 (2) D
Restricted Stock Unit (3) (3) Common Stock 13,250 (2) D
Explanation of Responses:
1. The RSUs vest in one year from the August 28, 2009 grant date.
2. Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Instruments, Inc.
3. The RSUs vest in 3 years after grant date (broken out by amount and corresponding grant date as follows: 5,000 on April 9, 2010, 4,000 on May 26, 2009, 4,250 on March 28, 2008 and 5,000 on March 5, 2007).
/s/Renee M. Donlan POA 05/11/2010
** Signature of Reporting Person Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes
and appoints each of  Kathleen F. Burke and Renee M. Donlan, signing
singly / jointly, the undersigned's true and lawful attorney in fact
to:

(1)  execute for and on behalf of the undersigned, in the undersigned's
capacity as an officer and/or director of MKS Instruments Inc. (the
?Company?), Forms 3, 4,  5 and 144 in accordance with Section 16(a) of
the Securities Exchange Act of 1934 and the rules thereunder;

(2)  do and perform any and all acts for and on behalf of the
undersigned which may be necessary or desirable to complete and execute
any such Forms, complete and execute any amendment or amendments thereto,
and timely file such form with the United States Securities and Exchange
Commission and any stock exchange or similar authority; and

(3)  take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney in fact, may be of
benefit to, in the best interest of, or legally required by, the
undersigned, it being understood that the documents executed by such
attorney in fact on behalf of the undersigned pursuant to this Power of
Attorney shall be in such form and shall contain such terms and
conditions as such attorney in fact may approve in such attorney in
fact's discretion.

The undersigned hereby grants to each such attorney in fact full power
and authority to do and perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the exercise of any of the
rights and powers herein granted, as fully to all intents and purposes
as the undersigned might or could do if personally present, with full
power of substitution or revocation, hereby ratifying and confirming
all that such attorney in fact, or such attorney in fact's substitute
or substitutes, shall lawfully do or cause to be done by virtue of this
power of attorney and the rights and powers herein granted.  The
ndersigned acknowledges that the foregoing attorneys in fact, in
serving in such capacity at the request of the undersigned, are not
assuming, nor is the Company assuming, any of the undersigned's
responsibilities to comply with Section 16 of the Securities Exchange
Act of 1934.

This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, 5 and 144 with
respect to the undersigned's holdings of and transactions in securities
issued by the Company, unless earlier revoked by the undersigned in a
signed writing delivered to the foregoing attorneys in fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney
to be executed as of this 5th day of May, 2010.

/s/ Paul Eyerman
____________________________
Signature
Name:_Paul Eyerman__________