Seventeen idiopathic parkinsonian patients ranging between 47 and 75 years of age were included in this study to investigate the effect and tolerance of lisuride on PD. The duration of this simple clinical study, which had no control group was 12 weeks. There was 50% relief in disability scores and ADL in 13 patients in the first group in the combined therapy for 12 weeks with lisuride added to L-DOPA plus benserazide (p < 0.01). Optimal lisuride doses added to L-DOPA plus benserazide varied between 0.1 and 0.8 mg (mean 0.5 +/- 0.2 mg). With the addition of lisuride to treatment, the L-DOPA plus benserazide dose was reduced in 6 of 13 by 38%. Monotherapy with lisuride resulted in 56% to 57% improvement in disability scores and 47% in relief in ADL. Dry mouth, nausea, weakness, postural hypotension, and headache were the most frequently encountered side effects of lisuride. These adverse effects disappeared in 3 or 4 days, depending on a slight decrease and following increase in the dose of lisuride and/or the development of tolerance. Not only will such a combined therapy contribute to the reduction of the end-of-dose inadequacies, on-off phenomena, wearing off, peak-dose dyskinesias, and similar motor fluctuations, it may also play a prophylactic role in their prevention or delay.