INTRODUCTION:Rasagiline (Azilect, AGN 1135) is a selective irreversible inhibitor of monoamine oxidase B (MAO-B). MAO-B regulates the brain concentrations of important neurotransmitters that are related to movement, emotion, and cognition. Oral rasagiline, as monotherapy or as adjunctive therapy to levodopa, was effective in the symptomatic treatment of adult patients with Parkinson's disease participating in double-blind, placebo-controlled, international studies. AREAS COVERED:This article reviews the reported adverse effects of rasagiline. A MEDLINE search was performed for all articles from 1990 to present, which reported any adverse effects from rasagiline or related references. We conducted an analysis of the adverse effects of rasagiline based on the reported clinical studies. Furthermore, we compared the incidence of adverse events in clinical trials for rasagiline and placebo. EXPERT OPINION:Among the most frequently reported adverse effects for rasagiline as monotherapy are headache, dizziness, and insomnia. Depression, dizziness, somnolence, and other sleep disorders are reported when used in combination therapy. Our analysis demonstrates that the most frequently reported adverse effects in trials did not occur more often with rasagiline than placebo. In conclusion, rasagiline is a well-tolerated MAO-B inhibitor that may help to achieve the desired level of clinical benefit in Parkinson's disease.