The efficacy and safety of pirlindole (300 mg/day), a new reversible inhibitor of monoamine oxidase A, have been evaluated in a multicentre placebo-controlled double-blind randomized trial in 103 in-patients suffering from unipolar major depression (DSM-III-R 296.2, 296.3) over a 42-day period after a run-in placebo period of 6 days. Pirlindole produced a significantly greater decrease than placebo in the Hamilton depression score (from day 28), the Hamilton anxiety score (from day 28) and the Montgomery-Asberg depression score (on day 42). On day 42, the Hamilton depression score was < or = 7, > or = 8 and < or = 15, or > or = 16 in 21%, 45% and 34%, respectively, in the placebo group compared to 72%, 24% and 3.4%, respectively, in the pirlindole group (P < 0.001). The differences between the two groups in terms of tolerance and safety were not statistically significant.