Inhibitors of phenylethanolamine N-methyltransferase (PNMT) and amphetamine were evaluated for their effects on the uptake of [3H]-norepinephrine (3H-NE) and the release of endogenous NE and dopamine (DA) from chopped rat brain tissues. Unlike amphetamine, all of PNMT inhibitors tested produced only slight inhibition of [3H]-NE uptake into chopped cerebral cortex. 2,3-Dichloro-alpha-methylbenzylamine (DCMB) and 7,8-dichloro-1,2,3,4-tetrahydroisoquinoline (SKF64139), but not 2-cyclooctyl-2-hydroxyethylamine (CONH) and 1-aminomethylcycloundecanol (CUNH) produced slight release of endogenous NE and DA from chopped hypothalami, but their effects were less pronounced than those produced by amphetamine.