Sixty-three patients with Parkinson's disease who failed bromocriptine therapy for various reasons were treated in an open-label trial of pergolide. The data were evaluated in a retrospective manner. Forty-six percent had a good response and tolerated the pergolide. A comparison of the outcomes regarding response and toxicity revealed that bromocriptine and pergolide act differently in individual patients. A trial of pergolide in Parkinsonian patients failing bromocriptine therapy may be therapeutically useful.