Autonomic dysfunction is often associated with the progression of Parkinson's disease (PD). The most frequent manifestations of autonomic dysfunction are cardiovascular symptoms, bladder and bowel dysfunction, and sudomotor dysfunction. However, sudomotor dysfunction in PD remains poorly understood. To evaluate sudomotor function in PD, we quantitatively measured sweating during untreated conditions in 20 patients with PD (age, 62 +/- 5 years) and in 10 age-matched control subjects (60 +/- 6 years). An evaporimeter can measure small amounts of water (g/m2h) evaporated from the body. This device was used to quantify sweating at different sites of the skin (forehead, arm, dorsal part of hand, chest wall, femur, and dorsal part of foot). Sweating demonstrated as amount of evaporated water (mean +/- SD g/m2h) was less in the patients with PD than in the control participants on the dorsal parts of the hand (13.7 +/- 5.2 vs. 23.9 +/- 5.5, p < 0.001) and foot (16.0 +/- 6.0 vs. 22.1 +/- 8.3, p < 0.05). On the dorsal part of the hand, sweating in the patients with PD at Yahr stages I and II was less than that in the control-Participants (15.2 +/- 6.3 vs. 23.9 +/- 5.5, p < 0.05). Sweating in the patients with PD at Yahr stages III and IV was less than that in the control participants on the dorsal parts of the hand (10.8 +/- vs. 2.7 vs. 23.9 +/- 5.5, p < 0.001), and foot (10.9 +/- 2.3 vs. 22.1 +/- 8.3, p < 0.005). Sweating on the dorsal part of the foot was less in the patients with PD at Yahr stages III and IV than that in those at Yahr stages I and II (10.9 +/- 2.3 vs. 18.4 +/- 6.1, p < 0.05). Sweating on the forehead in the patients with PD at Yahr stages I and II stage was slightly but not significantly less than that in the control participants (21.8 +/- 3.8 vs. 32.7 +/- 11.9, p < 0.2). Sweating on the forehead in the patients with PD at Yahr stages III and IV was sightly but not significantly greater than that in those at Yahr stages I and II (25.4 +/- 5.6 vs. 21.8 +/- 3.8, p < 0.2). Increased sweating on the forehead skin might compensate for decreased sweating on the extremital skin. Our results suggest that sudomotor dysfunction in PD primarily affects the distal parts of the upper and lower extremities. Sudomotor dysfunction affecting distal parts of the extremities worsens with increased severity of PD.