Abstract: An improved method and device are disclosed for diagnosing carpal tunnel syndrome. Direct pressure is applied to the median nerve as it passes through the carpal tunnel at the base of the wrist. Application of 100-200 mm mercury pressure to the nerve for thirty seconds produces numbness and paresthesias in the distribution of the median nerve distal to the carpal tunnel in patients having anatomic evidence of carpal tunnel syndrome. The disclosed device is a clamp having an opposing wrist support member and pressure application member. The distance between the support and pressure application members can be varied to alter the amount of pressure applied to the median nerve in the carpal tunnel. Use of the disclosed method and device provides a much more sensitive and specific clinical test for carpal tunnel syndrome than could previously be obtained with Phalen's test or Tinel's sign. Clinical use of this test can, in some cases, eliminate the need for electromyographic studies.