BACKGROUND Thoracoscopic sympathectomy is the most effective treatment for upper limb hyperhidrosis. However, this is offset by the occurrence of a high rate of side effects, such as embarrassing compensatory sweating. Anticipating that a technique that respects the sympathetic chain and divides only the rami communicantes may lead to fewer side effects, we assessed the technique described by R. Wittmoser, comparing it with conventional thoracoscopic sympathecomy. METHODS A total of 240 thoracoscopic sympathectomies were performed in 124 patients suffering from upper limb hyperhidrosis. Fifty-four patients underwent a conventional sympathectomy (group TS), 62 underwent division of the rami communicantes with respect to the main trunk (group SS), and 8 underwent both procedures (group TS/SS) because of accidental division of the chain during dissection. The mean follow-up is 8 months. RESULTS No recurrence was observed in group TS whereas six (5%) occurred in group SS (p < 0.05). The global rate of compensatory sweating was about the same in both groups: 72.2% in group TS and 70.9% in group SS. However, the rate of embarrassing or disabling compensatory sweating was significantly higher in group TS (50%) than in group SS (21%) (p < 0.001). CONCLUSIONS Although selective division of the rami communicantes results in a significant decrease in the rate of disturbing side effects, it also leads to recurrences that are usually not observed at that level in patients treated with the conventional technique. Therefore other means of achieving the ideal operation should be explored, that is, a technique associated with a high success rate but a minimal number of side effects.