The effects of paroxetine (20 and 40 mg/day) and amitriptyline (75 mg/day, used as an active control) on car driving and psychomotor function were compared with those of placebo in a double-blind, crossover study employing 16 healthy subjects. Performance testing occurred on the first and last day of each 8-day treatment series. Side-effects, sleep duration and sleep quality were rated daily. Amitriptyline produced severe drowsiness and strikingly impaired performance on nearly every test on the first day but its effects were practically gone after 1 week of treatment. Paroxetine 20 mg, the usual antidepressant dose, had no effect on performance. Paroxetine 40 mg did not affect road tracking but slightly impaired performance in some psychomotor tests in a persistent manner. Paroxetine had no effect on sleep following the 20 mg dose but reduced quality following the 40 mg dose. Side-effects that the administered drugs have in common were milder during paroxetine than amitriptyline treatment. However, some dose-related side-effects (e.g. nausea and delayed ejaculation) were only reported during paroxetine treatment.