Pergolide, a long-acting central dopamine agonist, was used as monotherapy in 16 parkinsonian patients. A mean daily dose of 6.3 mg resulted in 73% improvement of parkinsonian disability. Clinical improvement after acute administration of one dose of pergolide was similar to that observed after levodopa plus a peripheral decarboxylase inhibitor but at a dose 100 times lower (2.2 mg and 200 mg, respectively). The effect lasted twice as long (5 1/2 hours and 2 1/4 hours, respectively).