21. Subsidiaries of the registrant

WHOLLY OWNED SUBSIDIARIES

Keithley International Investment Corporation

28775 Aurora Road, Cleveland, Ohio 44139, U.S.A.

Keithley Foreign Sales Corporation

5 Norre Gade, Charlotte Amalie

St. Thomas, U.S. Virgin Islands 00801

FRANCE:  Keithley Instruments SARL

3 Allee des Garays

91127 Palaiseau Cedex

GERMANY:  Keithley Instruments GmbH

Landsberger Strasse 65

82110 Germering (Munich)

GREAT BRITAIN:  Keithley Instruments Ltd.

Unit 2 Commerce Park, Brunel Road

Theale, Berkshire RG7 4AB

ITALY:  Keithley Instruments SRL

Viale San Gimignano 38

20146 Milano

JAPAN:  Keithley Instruments KK

New Pier Takeshiba North Tower 13F

11-1, Kaigan 1-chome

Minato-ku, Tokyo 105-0022

NETHERLANDS:  Keithley Instruments BV

Postbus 559

4200 AN Gorinchem (Amsterdam)