We report on 2 patients with hyperhidrosis and decreased temperature of the leg on the unoperated side after unilateral retroperitoneal lymph node dissection. Both patients had a 4 to 5C difference in skin temperature of the feet, with the operated side being warm and dry compared to the nonoperated side. This condition is most likely due to a lesion of sympathetic fibers or ganglia located in close proximity to the retroperitoneal lymph nodes, resembling a unilateral lumbar sympathectomy. In addition, both patients had profuse sweating and a subjective feeling of coldness of the leg on the nonoperated side, which caused considerable discomfort. This latter phenomenon most likely represents a compensatory sympathetic hyperfunction due to the decreased sympathetic function in the other leg.