In a series of patients with clinically and neurophysiologically well defined carpal tunnel syndrome a randomization has been made into two groups, one for operation with internal neurolysis and a microscopical technique, and the other group for cutting of the carpal ligament (flexor retinaculum) alone. The two groups have been compared postoperatively regarding clinical and neurophysiological parameters. All patients improved, 89% in both groups considered themselves totally free of symptoms at follow-up examinations but there was no significant difference in any parameter between the two groups. As a conclusion the use of internal neurolysis cannot be recommended as a routine procedure in carpal tunnel syndrome.