Abstract Some patients with Parkinson’s disease (PD) suffer from autonomic dysfunction, even in the early stage of the disease. We examined the skin wrinkling response following immersion of the hands in warm water in 18 patients with hemiparkinsonism. This test evaluates the function of the sympathetic autonomic system. Mean age of the patients was 61 ± 10 and mean disease duration 5.5 ± 3.5 years. Both hands of each patient were immersed in warm water for 30 minutes and the number of skin ridges of the fingertip of each finger was counted. The results of each hand were compared to those of nine healthy controls. The mean number of the ridges of the less affected hand was significantly decreased as compared to the affected hand and controls (6.1 ± 6.8 vs 13.1 ± 6.8 and 15.3 ± 8.5, respectively; P < 0.01). These results suggest that autonomic dysfunction is prevalent in the less affected side of patients with PD and can be simply tested by the skin response test.