In a double-blind study carried out on elderly patients (older than 65 years) the efficacy and tolerability of the new antidepressant moclobemide was compared. Moclobemide belongs to a new class of substances called RIMA (Reversible inhibitor of the monoamine oxidase type A). Fluvoxamine, a selective reuptake-inhibitor of 5-HT, belongs to a class of antidepressants known for their better tolerability compared to tricyclic especially with elderly patients. Forty elderly patients (mean age 75 years) with major depression (according to DSM III) were randomized to receive either moclobemide (300 mg) or fluvoxamine (100 mg) twice daily. Dosages were increased when necessary on day 8, to a maximum of 450 mg moclobemide or 200 mg fluvoxamine and in most cases were maintained at these levels for the remainder of the study period (four weeks). Moclobemide was more effective than fluvoxamine showing a marked antidepressant effect and an earlier effect on psychomotor retardation. The two drugs were well tolerated showing a low incidence of side effects.