1 23. Consent of experts CONSENT OF INDEPENDENT ACCOUNTANTS ---------------------------------- We herby consent to the incorporation by reference in the Registration Statement on Form S-8 (No. 333-21999) of Keithley Instruments, Inc. of our report dated June 16, 2000 relating to the financial statements of Keithley Instruments, Inc. Retirement Savings Trust and Plan, which appears in this Form 11-K. /s/ PricewaterhouseCoopers LLP Cleveland, Ohio June 28, 2000