Mail Stop 6010 March 16, 2006 Mr. Mark J. Plush Vice President and Chief Financial Officer Keithley Instruments, Inc. 28775 Aurora Road Solon, Ohio 44139 		RE: 	Keithley Instruments, Inc. 			Form 10-K for fiscal year ended September 30, 2005 			File No. 1-9965 Dear Mr. Plush, 	We have completed our review of your Form 10-K and related filings and do not, at this time, have any further comments. Sincerely, 							Martin F. James 							Senior Assistant Chief Accountant