There are no precise criteria for the diagnosis of carpal tunnel syndrome (CTS): the history is useful but the value of the various provocative tests is questionable. The purpose of this study was to examine the diagnostic value of a new provocative test, the 'modified pneumatic compression test' in CTS. The study group consisted of 37 patients with 50 symptomatic CTS hands. A control group of 50 healthy volunteers was recruited. The diagnosis was based on a combination of the history, the clinical findings on examination and electrophysiological criteria. Sensitivity for the pneumatic compression and the modified pneumatic compression tests were 68% and 84%, respectively. Specificities for these tests were 97% and 95%, respectively. The modified pneumatic compression test demonstrated high sensitivity and specificity for CTS. This test facilitated the diagnosis and was easy to use. It may reduce referrals for neurophysiology testing, and so reduce costs.