Nerve Conduction studies are used not only in diagnosis of compression neuropathy, but also as a prognostic evaluation after is treatment. Authors analyzed the changes of nerve conduction studies in the 21 hands of 19 patients of carpal tunnel syndrome which was confirmed by clinical and electrodiagnostic methods, and treated by surgical release of transverse carpal ligament. The changes of nerve conduction and clinical studies were completed just before surgery, and at 2-week, 1-month, 3-month and 6-month of postoperative periods, and summarized as follows; 1. The distal sensory and motor latencies were significantly(P<0.05) improved at the 3-month of postoperative periods, respectively. 2. The sensory conduction velocities across the carpal tunnel was significantly(P<0.05) improved at the 6-month of postoperative periods. 3. The distal motor amplitude was significantly(P<0.05) improved at the 6-month of postoperative periods. 4. The changes in sensory conduction studies were more sensitive value for evaluation of patients with carpal tunnel syndrome. 5. The distal latencies reflected the progress of clinical improvement, accurately. These conduction studies are considerable value in the evaluation of the post-carpal tunnel release patient.