Quantitative electroencephalogram (QEEG) changes induced by the acute administration of moclobemide (200 mg) in patients with major depression include a transient increase in theta-activity, a slight augmentation of alpha-activity and a sustained increase in beta-activity. This QEEG profile distinguishes moclobemide from sedative antidepressants. A 42-day treatment with 400 mg/day of the drug produces a significant decrease in the late positive-complex peak latency of the event-related potentials, suggesting a positive effect on attention and cognitive functions.