We have investigated the autonomic function of 95 patients with Parkinson disease (PD) by testing their cardiovascular reflexes and compared the results with those of 53 healthy volunteers. 51.1% of the patients were on antiparkinsonian therapy. The patients showed a smaller heart rate response to deep breathing with a mean exhalation-inspiration difference of 87.73 +/- 7 (p: 0.0005), a smaller heart rate response to standing with a mean 30: 15 index of 1.18 +/- 0.25 (p: 0.01), and a smaller blood pressure rise to handgrip with a mean rise of 9.53 +/- 8.76 mmHg (p: 0.005). We found a higher percentage of patients with established sympathetic lesion (41% vs 34%) or atypical patterns of global autonomic function involvement (33% vs 26%), but the percentage of subjects with parasympathetic lesion was similar in both, patients and controls (16% vs 15%). We found no significant difference on cardiovascular performance between treated and untreated patients. The patients with autonomic impairment were older than the patients with normal autonomic function. Our findings suggest that patients with PD have a true autonomic dysfunction.