Lisuride at a mean daily dose of 3.2 mg was given to 15 untreated idiopathic Parkinson's disease patients. There were 10 dropouts, due mainly to inefficacy in the first months of therapy. The parkinsonian pattern in the patients who remained in the study for the full 4 years showed distinct improvement, which was maintained for less than 2 years. The patients did not develop "on-off" phenomena or abnormal involuntary movements during follow-up.