Para-methoxyamphetamine (PMA) was found to be ineffective in altering the levels of mouse brain DA and NE at doses of 3 and 10 mg/kg but a significant decrease in these amines was observed at 30 mg/kg. In contrast, all doses of PMA tested markedly elevated brain 5-HT and decreased brain 5-HIAA. PMA caused a dose related decrease in the accumulation of 14C-NE formed from 14C-tyrosine but increased the levels of 14C-NE formed from 14C-DOPA. Furthermore, PMA increased the accumulation of 14C-NM formed from 14C-tyrosine in a manner similar to d-amphetamine. Of the doses tested, only 30 mg/kg of PMA increased psychomotor activity.