Compensatory hyperhidrosis (CH) is the most troublesome side effect after T2 sympathectomy for palmar hyperhidrosis (PH). The aim of this study was to evaluate whether T4 ganglion interruption for PH is an effective approach that can simultaneously minimize the rate of CH. Between July 2001 and July 2003, 84 PH patients undergoing bilateral thoracoscopic T4 sympathectomy were followed up in the outpatient clinic and by telephone questionnaire. Rates of success, regret, CH, recurrence, and complications were recorded. The follow-up period ranged from 18 to 42 months. All excessive hand sweating was stopped. Only two patients had mild CH that did not affect their daily activities. No patients had recurrence or regret. The only other complication was that four patients had postoperative minimal residual pneumothorax, which needed no treatment. All patients were satisfied with the outcome. T4 sympathectomy was an effective method to cure PH. The success rate was 100%. The rate of CH was remarkably low compared with T2 sympathetic ganglionic interruption.