Phenylethylamine (PEA), 10, 50 and 100 microgram/rat ivc depressed the spontaneous and explorative motor activities, did not affect the body temperature and potentiated the action of hypnotics. The PEA-induced depression of motor activity was antagonized by spiperone, phenoxybenzamine, propranolol and, slightly, by alpha-MT. In rats with total chemical destruction of catecholamine neurons and in rats with selective lesion of dopamine neurons, PEA increased motor activity. Similar effect was observed after administration of reserpine, reserpine together with 6-hydroxydopamine and yohimbine. PEA potentiated the amphetamine and apomorphine stereotypy but inhibited amphetamine hypermotility: in the latter experiment slight periodical stereotyped head movements were observed. PEA did not affect haloperidol and fluphenazine induced catalepsy. It did not change the immobility period in the behavioral despair test. In doses of 0 . 1, 1 and 10 mg/kg iv it potentiated flexor reflex of the hind paw of the spinal rat. Phentolamine (10 mg/kg iv) and propranolol (5 mg/kg iv) slightly potentiated the stimulatory effect of PEA. In doses of 50 and 100 microgram ivc PEA did not affect the level and utilization of noradrenaline, and did not change the level of dopamine but depressed its utilization in the cerebral cortex, striatum and hippocampus.