Rasagiline (Azilect(®)) is an oral, second-generation, selective, irreversible monoamine oxidase-B (MAO-B) inhibitor approved in the US for the treatment of Parkinson's disease. In randomized, controlled trials, oral rasagiline 1 mg once daily was superior to placebo in the symptomatic treatment of early Parkinson's disease, both as monotherapy or as an adjunct to dopamine agonists. Comparisons of early-start and delayed-start treatment suggested a disease-modifying effect for rasagiline, but the results were equivocal. Rasagiline 0.5 or 1 mg/day was also superior to placebo as adjunctive therapy to levodopa in Parkinson's disease patients with motor fluctuations. Rasagiline was generally well tolerated in clinical trials, displaying a placebo-like tolerability profile in several studies. Cost-utility studies predicted that rasagiline, either as monotherapy or adjunctive therapy, would be a cost-effective treatment option. Therefore, oral rasagiline is a valuable therapeutic option for use in all stages of Parkinson's disease.