The dopamine agonist, CQP 201-403, was administered to 10 patients in an open label fashion with rapid dosage escalation during hospitalization. Assessed over an average of 20 days, significant improvement occurred in bradykinesia, rigidity, and postural instability. Tremor did not occur in sufficient frequency in this group of patients to be accurately assessed. The most serious adverse effect encountered was prolonged confusion with psychosis. This study suggests that CQP 201-403 may be of value in the treatment of Parkinson's disease.