BACKGROUND: Compensatory hyperhidrosis is the most troublesome side effect and the leading cause of regret with sympathetic surgery. A new classification is proposed to make the procedure more selective and to minimize the side effects and regret rate. Also, a proposed mechanism for compensatory hyperhidrosis is discussed. METHODS: Between January 2002 and July 2003, 464 patients with various sympathetic disorders underwent thoracoscopic sympathectomy/sympathicotomy (ETS) or sympathetic block by clipping (ESB) at various levels according to the authors' classification. The surgery was performed on an outpatient basis. The rates of success, compensatory hyperhidrosis, and regret were recorded. RESULTS: All the patients were followed up for 17 to 35 months. All excessive sweating was effectively stopped to varying degrees. The 25 patients with palmar hyperhidrosis who insisted on receiving ETS of T4 experienced no compensatory hyperhidrosis. Of the 54 patients with facial blushing who received ESB of T2, 23 experienced compensatory hyperhidrosis. Nine patients expressed regret and requested removal of the clips. Of the 33 patients with craniofacial hyperhidrosis who received ESB of T3, 9 experienced compensatory hyperhidrosis. Three expressed regret, and reverse procedures were performed. For 324 patients with palmar hyperhidrosis receiving ESB of T4, no compensatory hyperhidrosis was found. Only two expressed regret because of discomfort. No compensatory hyperhidrosis or regret was noted with 28 patients who received ESB of T5 for axillary sweating. There was no recurrence in the entire series. CONCLUSIONS: Different procedures are recommended for different sympathetic disorders according to the classification. The higher the level of sympathetic ganglion blockade, the higher is the regret rate. Therefore, for T2 and T3 ganglion, endoscopic thoracic sympathetic block by the clipping method is strongly recommended because of its reversibility.