The stimulatory effect of cocaine on locomotor activity and on dopamine efflux from the ventral striatum was studied in rats chronically treated with the antidepressant imipramine. Chronic imipramine (20 mg/kg per day for 3 weeks) potentiated by about 2-fold cocaine-stimulated motor activity and extracellular dopamine concentrations. The results indicate that chronic imipramine facilitates mesolimbic dopamine neurotransmission by potentiating the mechanism which is thought to mediate the rewarding effects of cocaine.