We reviewed the clinical and autonomic features of all patients with extrapyramidal and cerebellar disorders studied in the Mayo Autonomic Reflex Laboratory from 1983 to 1989. Patients were grouped into the following categories (number in parentheses): Parkinson's disease (35); parkinsonism-plus (54); multiple system atrophy (75); hereditary multisystem degenerations (eleven); progressive supranuclear palsy (32); non-familial cerebellar degeneration (eleven); nonspecific sporadic multisystem degeneration (73). Severe autonomic failure occurred in 97% of patients with multiple system atrophy and 53% of the nonspecific sporadic multisystem degeneration patients respectively. Autonomic involvement was mild or absent in Parkinson's disease while parkinsonism-plus and non-familial cerebellar degeneration patients had moderate autonomic failure. Orthostatic blood pressure reduction, percentage of anhidrosis on thermoregulatory sweat test, quantitative sudomotor axon reflex test, forearm response and heart rate response to deep breathing strongly regressed with severity. A response to levodopa treatment in patients with parkinsonism was more likely if cerebellar signs and cognitive deficits were absent. The presence of levodopa induced dyskinesia was also a marker for a clinically favourable levodopa response. We conclude that there is a spectrum of autonomic involvement in these degenerative disorders and that autonomic studies are useful in separating them and monitoring their course.