In the first part of this study 17 patients with a clinically clear-cut carpal tunnel syndrome but with normal electrophysiological findings have been controlled after 1 to 3 years. In 12 of these patients an other cause of the complaints could be found. In 2 patients no definite diagnosis could be made and in 3 the previous diagnosis was considered to be corrected. Control electromyography was pathological in 2 of them and 1 patient was symptom-free after the operation. In the second part 133 hands with clinical symptoms of a carpal tunnel syndrome were examined clinically and electrophysiologically. In the group of patients with pathological electrophysiological findings there were significantly more objective signs than in those with normal EMG findings. In 13 of these patients which could be followed an other diagnosis could be made. It was not possible to establish a clinical index for the carpal tunnel syndorme. For a definite diagnosis, positive clinical and electrophysiological findings are required.