Summary The effects of haloperidol on striatal dopamine (DA), homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) content, hypothermia and catalepsy have been studied in rats. Haloperidol (0.5, 1.0, 2.5 and 5.0 mg/kg i.p.) induces an increase of DOPAC and HVA levels in corpus striatum as well as catalepsy. Higher doses (2.5 and 5.0 mg/kg) induce also a significant decrease of DA content and a lowering of body temperature. No clearcut relationship has been found among striatal content in DA, its acid metabolites and the severity of the motor symptoms.