The influence of the type, duration, severity and levodopa treatment of Parkinson's disease on autonomic involvement has been assessed. The Valsalva manoeuvre, deep breathing, handgrip and orthostatic tests were performed in 50 patients with Parkinson's disease and in a control group of 30 healthy subjects. No attempt was made to classify further patients with parkinsonian features into groups such as the Shy-Drager syndrome or multiple system atrophy. All test results were significantly smaller in patients than in healthy subjects. The diastolic pressure increase during handgrip was significantly smaller in akinetic-rigid than in tremor-akinetic-rigid type patients. The Valsalva ratio and orthostatic test results were significantly smaller in patients with longer duration than in those with shorter duration of disease. All test results except those of the orthostatic test were significantly smaller in patients with the more severe form than in those with the less severe form of disease. Comparing test results of levodopa-treated and -untreated patients no significant differences were found. Our studies in parkinsonian patients suggest that (1) sympathetic impairment is more pronounced in akinetic-rigid than in tremor-akinetic-rigid type patients; (2) sympathetic impairment occurs early, whereas parasympathetic impairment develops later; (3) sympathetic and parasympathetic impairment parallels the severity of disease; (4) orthostatic parameters are more duration-sensitive than severity-sensitive; (5) chronic levodopa treatment does not markedly influence cardiovascular autonomic responses.