The DOPAC/dopamine and HVA/dopamine ratios in extracted whole tissue were determined to obtain an index of dopaminergic activity in various rat brain regions 24 h following 10 days' treatment with haloperidol (0.5 and 2 mg/kg) or sulpiride (10 and 100 mg/kg). Both neuroleptics caused a reduction in the metabolite/amine ratio in nucl. accumbens but not frontal cortex or substantia nigra. Haloperidol, but not sulpiride significantly reduced the HVA/dopamine ratio in striatum. A region-specific action of neuroleptics on brain dopamine neurons is discussed.