Rats were administered [3H]spiperone (SP: spiroperidol) by tail vein injection and 2 h later the brain was processed for light microscopic autoradiography. High densities of autoradiographic grains were found in all areas known to have a dopaminergic innervation, including the olfactory tubercles, nucleus accumbens, nucleus caudate-putamen, lateral septum, zona incerta, nucleus subthalamicus, arcuate nucleus, nucleus of the central amygdala, areas in the ventral tegmentum and the claustrum. There were also increased autoradiographic grain densities in other areas such as the midbrain and the frontal cortex indicating that binding occurred to other neurotransmitter receptors besides dopamine receptors. These studies delineate with a high resolution at an anatomical level the major binding sites for neuroleptic drugs in the forebrain. They suggest which areas of the brain are the most involved in neuroleptic drug action and they add further evidence that important regions are those receiving a dense dopaminergic innervation.