Ropinirole is a novel, nonergoline, selective D2-type dopamine agonist developed to treat Parkinson's disease. Safety data from therapeutic studies involving 1364 patients receiving ropinirole are reported (mean daily dose 8.7 mg, early therapy; 8.2 mg adjunct therapy). In early therapy, the emergent adverse experiences more common with the ropinirole group compared with placebo were nausea, somnolence, leg edema, abdominal pain, vomiting, dyspepsia, and hallucinations. In adjunct therapy, they were dyskinesia, nausea, hallucinations, and confusion. Most adverse experiences were mild and associated with a similar withdrawal rate compared with the placebo group. Except for hallucinations, the incidence of emergent adverse experiences decreased with time, despite increasing doses. Long-term adverse experiences particularly associated with ergoline-type dopamine agonists have so far not been observed with ropinirole. Only 1.2% of patients receiving ropinirole developed dyskinesia compared with 11.2% receiving L-dopa in early therapy over a mean period of 17 months. There were no clinically significant changes in cardiovascular parameters or laboratory data. The incidence of adverse experiences in the bromocriptine group was low, possibly because of a slow titration scheme and low average dose. Overall, the safety profile of ropinirole appears similar to that of other dopamine agonists. Clinical studies are continuing to assess the long-term safety and efficacy of ropinirole.