Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
GRISWOLD JAMES B
  2. Issuer Name and Ticker or Trading Symbol
KEITHLEY INSTRUMENTS INC [KEI]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
KEITHLEY INSTRUMENTS, INC., 28775 AURORA ROAD
3. Date of Earliest Transaction (Month/Day/Year)
05/13/2010
(Street)

SOLON, OH 44139
4. If Amendment, Date 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
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Shares 05/13/2010   A   1,417 A $ 0 35,164 D  
Common Shares               20,000 D (1)  

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Common Stock Option $ 36.85             08/18/2001 02/17/2011 Common Stk 10,000   10,000 D  
Common Stock Option $ 19.23             08/17/2002 02/16/2012 Common Stk 10,000   10,000 D  
Common Stock Option $ 23.13             08/15/2004 02/14/2014 Common Stk 10,000   10,000 D  
Common Stock Option $ 16.67             05/13/2005 02/12/2015 Common Stk 10,000   10,000 D  
Phantom Stock Units (2)               (3)   (3) Common Stock 59,045.17 (2)   59,045.17 (2) D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
GRISWOLD JAMES B
KEITHLEY INSTRUMENTS, INC.
28775 AURORA ROAD
SOLON, OH 44139
  X      

Signatures

 Mark J. Plush, Attorney-in Fact   05/14/2010
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(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).
(1) Roth IRA
(2) Phantom shares were acquired on various dates (beginning 09/19/1995) with prices ranging from $2.469 to $64.00.
(3) The phantom stock units were accrued under the Keithley Instruments, Inc. Deferred Stock Plan and are to be settled in ten annual installments in common stock or cash upon the retirement from the Board of the reporting person; retirement date is not yet known.

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