OBJECTIVE To compare two surgical techniques (denervation levels) for sympathectomy using video-assisted thoracoscopy to treat palmar hyperhidrosis in the long-term. METHODS From May 2003 to June 2006, 60 patients with palmar hyperhidrosis were prospectively randomized for video-assisted thoracoscopic sympathectomy at the T2 or T3 ganglion level. They were followed for a mean of 20 months and were evaluated regarding their degree of improvement of palmar hyperhidrosis, incidence and severity of compensatory hyperhidrosis and its evolution over time, and quality of life. RESULTS Fifty-nine cases presented resolution of the palmar hyperhidrosis. One case of therapeutic failure occurred in the T3 group. Most of the patients presented an improvement in palmar hyperhidrosis, without any difference between the groups. Twenty months later, all patients in both groups presented some degree of compensatory hyperhidrosis but with less severity in the T3 group (p = 0.007). Compensatory hyperhidrosis developed in most patients during the first month after the operation, with incidence and severity that remained stable over time. An improvement in quality of life was seen starting from the first postoperative evaluation but without any difference between the groups. This improvement was maintained until the end of the follow-up. CONCLUSION Both techniques were effective for treating palmar hyperhidrosis. The most frequent complication was compensatory hyperhidrosis, which presented stable incidence and severity over the study period. Sympathectomy at the T3 level presented compensatory hyperhidrosis with less severity. Nevertheless, the improvement in quality of life was similar between the groups.