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 *
PLUSH MARK J
  2. Issuer Name and Ticker or Trading Symbol
KEITHLEY INSTRUMENTS INC [KEI]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
VP, CFO
(Last)
(First)
(Middle)
KEITHLEY INSTRUMENTS, INC., 28775 AURORA ROAD
3. Date of Earliest Transaction (Month/Day/Year)
10/27/2010
(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 01/06/2010   J(1)   8 A $ 4.5527 42,738 D  
Common Shares 04/06/2010   J(1)   5 A $ 6.587 42,743 D  
Common Shares 07/06/2010   J(1)   12 A $ 8.98 43,947 (2) D  
Common Shares 07/16/2010   J(1)   429 A $ 8.388 44,376 D  
Common Shares 10/05/2010   J(1)   5 A $ 21.447 44,381 D  
Common Shares 10/21/2010   G   2,300 D $ 0 42,081 D  
Common Shares 10/27/2010   M   12,000 (3) A (3) 54,081 D  
Common Shares 10/27/2010   F   3,834 (4) D $ 21.53 50,247 D  
Restricted Shares (5)               952 D  
Common Shares 01/06/2010   J(1)   3 A $ 4.5527 1,339 I Trust (6)
Common Shares 04/06/2010   J(1)   3 A $ 6.587 1,342 I Trust (6)
Common Shares 07/06/2010   J(1)   6 A $ 8.98 1,348 I Trust (6)
Common Shares 10/05/2010   J(1)   2 A $ 21.447 1,350 I Trust (6)

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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 Share Option $ 18.41             07/25/2003(7) 07/24/2011 Common Shares 38,000 (8)   38,000 (8) D  
Common Share Option $ 13.76             07/24/2004(9) 07/23/2012 Common Shares 25,029   25,029 D  
Common Share Option $ 16.12             08/10/2005(10) 07/18/2013 Common Shares 33,000   33,000 D  
Common Share Option $ 18.75             02/15/2005(7) 07/16/2014 Common Shares 28,000   28,000 D  
Common Share Option $ 15.05             10/04/2007(9) 10/03/2015 Common Shares 10,400   10,400 D  
Common Share Option $ 9.12             11/09/2009(9) 11/09/2017 Common Shares 12,700   12,700 D  
Performance Award Unit (3) 10/27/2010   M     9,600 (3) 09/30/2010(3)   (3) Common Shares 9,600 (3) $ 0 (3) 0 (3) D  
Common Stock Option $ 2.99             02/06/2011(9) 02/06/2019 Common Shares 27,500   27,500 D  
Restricted Unit Award $ 0               (11)   (11) Common Shares 4,600   4,600 D  
Common Stock Option $ 4.26             12/04/2011(9) 12/04/2019 Common Shares 22,250   22,250 D  
Performance Award Unit $ 0             09/30/2012(12)   (12) Common Shares 22,250 (12)   22,250 (12) D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
PLUSH MARK J
KEITHLEY INSTRUMENTS, INC.
28775 AURORA ROAD
SOLON, OH 44139
      VP, CFO  

Signatures

 Mark J. Plush   10/29/2010
**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) Acquired through Employee Stock Purchase and Dividend Reinvestment Plan.
(2) Includes 1,192 shares for which restrictions lapsed on June 1, 2010, which were previously reported as restricted shares
(3) Each Performance Award Unit represented the right to receive one common share. The number of units initially awarded was a target (as shown in Table II), and the actual number of units that vested and converted to shares (which could range from 0 shares to twice the target number of shares) was based upon: a) the Company's revenue growth as compared to a defined Peer Group and, b) the Company maintaining an acceptable level of profitability during the performance period which ended on September 30, 2010. Based on the Company's performance, the units converted into a number of shares equal to 1.25 times the target number.
(4) Shares issuable upon vesting of Performance Award Units were withheld to settle associated tax liabilities.
(5) Restricted Shares will become fully vested on June 1, 2011
(6) Christopher M. Plush Trust, Virginia A. Plush Trustee
(7) Option became fully vested on February 15, 2005
(8) Pursuant to a domestic relations order, the reporting person is deemed to hold 16,251 options for his former spouse and may exercise the option solely upon the direct of his former spouse who is entitled to the shares issued upon exercise. The reporting person disclaims beneficial ownership with respect to the options held for the benefit of his former spouse.
(9) Date reported applies to 50% of total, one-half of the balance is then exercisable in each succeeding year.
(10) Option became fully vested on August 10, 2005
(11) Restricted unit awards will become fully vested on February 6, 2013. Common shares represented by such vested restricted unit awards will be delivered promptly after such vesting date.
(12) Each Performance Award Unit represents a right to receive one common share. The number of units comprising the initial award are adjusted (ranging from a maximum of twice the number of units comprising the initial award, to a minimum of no units), based on award program metrics that compare the Company's total shareholder return performance occurring during the Measurement Period to comparable total shareholder return performance reported by companies in the Russell Microcap Index. Awarded units earned based on these metrics as of September 30, 2012 (the vesting date) are converted to shares under the Plan and will be issued on or before December 31, 2012.

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