Objectives: levodopa improves the quality of life in parkinsonian patients, however long term response is compromised by the emergence of motor fluctuations and dyskinesias. The aim of this study was to compare the occurrence of motor fluctuations and dyskinesias in previously untreated patients assigned to receive levodopa, a dopamine agonist or deprenyl.Thirty-five neurological departments in Italian hospitals participated in this randomized open trial. Patients with Parkinson's disease, who required the initiation of an effective antiparkinsonian treatment, were randomly assigned to receive levodopa, dopamine agonists or deprenyl. The end-points were motor dyskinesias and motor fluctuations occurring in a median follow-up period of about 3years.After a median follow-up of 34months, motor fluctuations and dyskinesias were less frequent in patients assigned to a dopamine agonist or deprenyl than in patients assigned to levodopa (relative risk [RR] 0.5, 95% confidence interval [95% CI] 0.3-0.8, and RR=0.6, 95% CI 0.3-0.9, respectively), but dopamine agonists were less effective and less well tolerated than levodopa. The lower frequency of motor fluctuations in patients assigned to deprenyl was no longer statistically significant when prognostic predictors were considered in a multivariable analysis. Long-term mortality did not differ in the three arms of the study. Dopamine agonists and deprenyl can be considered as an alternative to levodopa for starting treatment in Parkinson's disease patients. However, on clinical grounds, only small advantages are expected over the traditional therapy initiation with levodopa.