Twenty-eight patients with Parkinson disease (PD) were treated with bromocriptine for at least 2 years (mean, 2.8 years; range, 2 to 5 years). All of them had first been treated with levodopa (alone or combined with carbidopa, as Sinemet) for 7.4 years (range, 1 to 10 years). At the time bromocriptine was started, all were showing increasing disability. In these patients, attempts to increase levodopa resulted in adverse effects, and attempts to decrease levodopa resulted in increased parkinsonism. Bromocriptine (mean daily dose, 56 mg) was added to levodopa and resulted in improvement of at least one stage (Hoehn and Yahr scale) in 21 of the patients. After 2 years, five of these patients continue to maintain this improvement. The remaining patients, although there has been deterioration, maintain some of their original improvement. Bromocriptine, when added to levodopa, results in improvement that is maintained, in part, for at least 2 years. The ratio of bromocriptine to levodopa has to be periodically readjusted.