Only by adequate controlled studies can we be certain of the value of the different therapeutic choices available for the treatment of patients with PD. What may look favorable on preliminary open-label trials may not be confirmed on more rigorous controlled, randomized trials. This appears to be the case when reviewing the evidence for using dopamine agonists in early PD. Patients and clinicians await the results of the large double-blind, multicenter trial that compared bromocriptine alone, L-DOPA alone, and the two drugs in combination. Similarly, we await the results of a large multicenter, controlled trial comparing standard Sinemet and Sinemet CR in de novo patients with Parkinson's disease. The DATATOP study provided proof that selegiline can delay the need for L-DOPA, but it also showed for the first time that this drug has symptomatic effects in early PD. DATATOP failed to find conclusively a protective effect from selegiline. The long-running controversy whether L-DOPA is the culprit or the bystander in producing motor response fluctuations and the more recent concern as to whether it can hasten the progression of PD by producing increasing oxidative stress need to be answered; a prospective, controlled clinical trial might be able to provide these answers.