Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy. It is mainly due to the compression of median nerve at the wrist and it may be idiopathic or secondary to different rheumatic or non rheumatic diseases, including occupational activities. Since signs and symptoms of CTS are characteristic, a careful examination of the affected patient may be very satisfactory for the diagnosis, in particular by means of some manoeuvres. In this review we described and commented the tests considered most useful in the diagnosis of CTS. We also analysed the diagnostic values of electromyography, the most important electrodiagnostic study for the CTS.