Seventeen out of 20 inactive and emotionally withdrawn schizophrenic patients under long-term neuroleptic treatment completed a double-blind cross-over investigation of the possible activating effect of maprotiline, a relatively specific noradrenaline-reuptake inhibitor, compared with that of placebo. Each treatment phase lasted 8 weeks. No significant differences with respect to either the level of activity or schizophrenic symptoms were found between maprotiline (mean dose 138 mg/day) and placebo. Maprotiline provoked a slight psychotic exacerbation in one patient and sedation in another, four patients developed orthostatic hypotension, and two patients had an epileptic seizure. In the light of this and other studies, it must be concluded that antidepressant drugs do not represent any therapeutic advance in the treatment of inactive schizophrenic patients receiving neuroleptics.