Ownership Submission
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, 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 *
  DANAHER CORP /DE/
 2. Date of Event Requiring Statement (Month/Day/Year)
09/29/2010		 3. Issuer Name and Ticker or Trading Symbol
KEITHLEY INSTRUMENTS INC [KEI]
(Last)
(First)
(Middle)
2099 PENNSYLVANIA AVENUE, 12TH FLOOR		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

WASHINGTON, DC 20006		 6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
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)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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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 of Derivative Security: 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
Class B Common Shares (1)   (1)   (1) Common Shares 0 $ (1) I See Footnote (1)

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
DANAHER CORP /DE/
2099 PENNSYLVANIA AVENUE
12TH FLOOR
WASHINGTON, DC 20006		     X    
Aegean Acquisition Corp.
2099 PENNSYLVANIA AVENUE
12TH FLOOR
WASHINGTON, DC 20006		     X    

Signatures

/s/ James F. O'Reilly, Associate General Counsel and Secretary, Danaher Corporation /s/ James F. O'Reilly, Vice President and Secretary, Aegean Acquisition Corp. 10/06/2010
**Signature of Reporting Person Date

Explanation of Responses:

* 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).
(1) This Form 3 is being filed as a result of that certain Voting Agreement, dated as of September 29, 2010, by and among Danaher Corporation ("Parent"), Aegean Acquisition Corp. ("Merger Sub") and Keithley Investment Co. Limited Partnership ("Partnership"), covering such number of the Partnership's Class B common shares representing 19.99% of the voting power of the Issuer. The Voting Agreement was entered into in connection with the proposed acquisition of the Issuer by Parent and Merger Sub. For additional information regarding the Voting Agreement and the acquisition of the Issuer, see Schedule 13D filed by Parent and Merger Sub with the Securities and Exchange Commission on October 7, 2010. Parent and Merger Sub expressly disclaim any beneficial ownership of the Issuer's common shares and Class B common shares.
 
Remarks:
Exhibit 99 - Joint Filer Information
Name: Aegean Acquisition Corp.
Address: 2099 Pennsylvania Avenue, 12th Floor
Washington, DC 20006
Designated Filer: Danaher Corporation
Issuer & Ticker Symbol: Keithley Instruments, Inc. (NYSE: KEI)
Date of Event Requiring Statement: September 29, 2010

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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