A randomized double-blind, multicenter 6-week study was undertaken in 80 depressed patients to compare the effects of moclobemide, a selective and reversible monoamine oxidase-A inhibitor (300 mg daily), and maprotiline (75 mg daily). Efficacy was assessed by Hamilton Depression Rating Scale (HDRS) and Clinical Global Impression (CGI). Tolerability was assessed by adverse events reports. After 6 weeks of therapy, both groups of patients showed significant improvement in HDRS and CGI. Speed of onset of action was faster with moclobemide (significant difference at week 3, p = 0.025). There was a significant reduction of depression ratings (HDRS) in both the moclobemide and maprotiline group in all types of depression according to ICD-9 criteria (major depressive disorder, neurotic depression and adjustment-prolonged depressive reaction). Significantly fewer patients in the moclobemide group reported adverse events (28.9% compared with 70.2%) including weight gain (2.6% compared to 21.6%). Anticholinergic side effects were less frequent with moclobemide. It is concluded that both drugs are at least equivalent in terms of therapeutic efficacy, but moclobemide is better tolerated.