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
                                                                                  
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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(f) of the Investment Company Act of 1940
                      

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 (MM/DD/YYYY)

10/27/2010
(Street)

SOLON, OH 44139
(City)        (State)        (Zip)
4. If Amendment, Date Original Filed (MM/DD/YYYY)

 
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 Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3) 		2. Trans. Date 2A. Deemed Execution Date, if any 3. Trans. 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   1/6/2010     J (1)    8   A $4.5527   42738   D    
Common Shares   4/6/2010     J (1)    5   A $6.587   42743   D    
Common Shares   7/6/2010     J (1)    12   A $8.98   43947   (2) D    
Common Shares   7/16/2010     J (1)    429   A $8.388   44376   D    
Common Shares   10/5/2010     J (1)    5   A $21.447   44381   D    
Common Shares   10/21/2010     G    2300   D $0.00   42081   D    
Common Shares   10/27/2010     M    12000   (3) A   (3) 54081   D    
Common Shares   10/27/2010     F    3834   (4) D $21.53   50247   D    
Restricted Shares   (5)                952   D    
Common Shares   1/6/2010     J (1)    3   A $4.5527   1339   I   Trust   (6)
Common Shares   4/6/2010     J (1)    3   A $6.587   1342   I   Trust   (6)
Common Shares   7/6/2010     J (1)    6   A $8.98   1348   I   Trust   (6)
Common Shares   10/5/2010     J (1)    2   A $21.447   1350   I   Trust   (6)

Table II - Derivative Securities Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security
(Instr. 3) 		2. Conversion or Exercise Price of Derivative Security 3. Trans. Date 3A. Deemed Execution Date, if any 4. Trans. 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 7. Title and Amount of Securities Underlying Derivative Security
(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                    7/25/2003   (7) 7/24/2011   Common Shares   38000   (8)   38000   (8) D    
Common Share Option   $13.76                    7/24/2004   (9) 7/23/2012   Common Shares   25029     25029   D    
Common Share Option   $16.12                    8/10/2005   (10) 7/18/2013   Common Shares   33000     33000   D    
Common Share Option   $18.75                    2/15/2005   (7) 7/16/2014   Common Shares   28000     28000   D    
Common Share Option   $15.05                    10/4/2007   (9) 10/3/2015   Common Shares   10400     10400   D    
Common Share Option   $9.12                    11/9/2009   (9) 11/9/2017   Common Shares   12700     12700   D    
Performance Award Unit     (3) 10/27/2010     M         9600   (3)   9/30/2010   (3)   (3) Common Shares   9600   (3) $0.00   (3) 0   (3) D    
Common Stock Option   $2.99                    2/6/2011   (9) 2/6/2019   Common Shares   27500     27500   D    
Restricted Unit Award   $0.00                      (11)   (11) Common Shares   4600     4600   D    
Common Stock Option   $4.26                    12/4/2011   (9) 12/4/2019   Common Shares   22250     22250   D    
Performance Award Unit   $0.00                    9/30/2012   (12)   (12) Common Shares   22250   (12)   22250   (12) D    

Explanation of Responses:
( 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.

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


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 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).
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