OBJECTIVE: This study evaluates the role of thoracoscopic T3 sympathicotomy for the treatment of primary hyperhidrosis and the prevention of compensatory hyperhidrosis. METHODS: Thoracoscopic T3 sympathicotomy was performed on 27 patients with either isolated palmar hyperhidrosis (n=24) or in combination with axillary hyperhidrosis (n=3), from February 1999 to February 2002. In the case of combined palmar and axillary hyperhidrosis, additional coagulation of T4 sympathetic ganglion was performed. The mean follow-up period was 26.7 months. Operative results were determined on the basis of complications, compensatory hyperhidrosis, and patient satisfaction. RESULTS: The immediate postoperative results showed that all 24 patients with palmar hyperhidrosis reported complete alleviation of their symptoms. One patient with palmar and axillary hyperhidrosis for whom the axillary hyperhidrosis was not completely resolved underwent a second T4 sympathicotomy one month after first operation. There were two patients who suffered mild compensatory hyperhidrosis(7.4%). All 27 patients reported a high long-term satisfactory rate (average score; 7.93/10). One patient required a chest tube for treating pneumothorax. Other complications such as Horners syndrome, intercostal neuralgia, gustatory hyperhidrosis, and pulmonary edema were not observed. CONCLUSION: Thoracoscopic limited T3 sympathicotomy is an effective method to treat primary hyperhidrosis with a low rate of compensatory hyperhidrosis and a high rate of long-term satisfaction.