Dopamine agonists (DAs) have been shown to be effective as monotherapy in early stages of Parkinson's disease (PD) and as an adjunctive treatment to levodopa in advanced PD. Since bromocriptine, an ergot compound, was introduced as the first commercially available DA more than 25 years ago, additional DAs have become available for clinical use. There is a remarkable paucity of data, however, that would guide clinicians in their decision process to select the most appropriate DAs. We discuss the theoretical basis for comparing the various DAs, and provide a concise analysis and summary of comparative trials of DAs in PD.