Keithley Instruments to Present at 2010 Thomas Weisel Partners Technology & Telecom Conference

Keithley Instruments, Inc. (NYSE:KEI), a world leader in advanced electrical test instruments and systems, today announced that Joseph P. Keithley, Chairman, President and Chief Executive Officer, along with Mark J. Plush, Vice President and Chief Financial Officer, will speak to the investment community at the Thomas Weisel Partners 2010 Technology & Telecom Conference to be held at The Fairmont Hotel, in San Francisco, California. The presentation will take place on Tuesday, February 9, 2010, at 10:55 a.m. Pacific Time (1:55 p.m. Eastern Time).

Interested investors can access the live webcast of the presentation through the Keithley Instruments website at http://ir.keithley.com. A replay of the webcast will be available for approximately 30 days.

About Keithley Instruments, Inc.

With more than 60 years of measurement expertise, Keithley Instruments has become a world leader in advanced electrical test instruments and systems. Our customers are scientists and engineers in the worldwide electronics industry involved with advanced materials research, semiconductor device development and fabrication, and the production of end products such as portable wireless devices. The value we provide them is a combination of products for their critical measurement needs and a rich understanding of their applications to improve the quality of their products and reduce their cost of test.