In the tarsal tunnel syndrome, the posterior tibial nerve is entrapped beneath the flexor retinaculum and deep fascia along the medial border of the foot. This syndrome is not recognized as readily as its counterpart in the upper extremity, the carpal tunnel syndrome. Seventeen patients with compression of the posterior tibial nerve were seen during the past 15 years; 16 have had surgical decompression. Entrapment has resulted from post-traumatic fibrosis, chronic compression from fascial bands, and entrapment by the abductor hallucis muscle. Electromyographic studies have aided diagnosis. Treatment has ranged from local steroid injection and weight reduction to surgical decompression of the posterior tibial nerve. The most consistent and satisfactory results have been observed after surgical decompression.