Exhibit 10(ee)
FOURTH AMENDMENT TO
THE KEITHLEY INSTRUMENTS, INC.
SUPPLEMENTAL DEFERRAL PLAN
Dated September 1, 1999
     FOURTH AMENDMENT, dated as of December 10, 2007 (the “Fourth Amendment”) to
the Keithley Instruments, Inc. Supplemental Deferral Plan dated as of
September 1, 1999 (the “Plan”). Capitalized terms used and not otherwise defined
herein shall have the meaning ascribed to them in the Plan.
     1. Amendments. The Plan is hereby amended as follows:
          (a) By deleting the definition of “Minimum Eligible Compensation
Level” in the Definition section of the Plan in its entirety and inserting in
lieu thereof the following “Minimum Eligible Compensation Level” definition:
          “Minimum Eligible Compensation Level. For the Plan Year starting
January 1, 2008, Compensation of at least $120,000 as determined for the
preceding Calendar Year.”
     2. General.
          (a) Except as expressly amended hereby, the provisions of the Plan are
and shall remain in full force and effect.

            KEITHLEY INSTRUMENTS, INC.
      By:   /s/ Mark J. Plush       Name:   Mark J. Plush        Title:   Vice
President and Chief Financial Officer