The distribution of histamine H1, H2 and H3 receptors in postmortem human and rhesus monkey brain was examined using receptor autoradiography. [125I]Iodobolpyramine, [125I]iodoaminopotentine and [3H](R) alpha-methylhistamine were used as ligands to label H1, H2 and H3 receptors respectively. The 3 receptor subtypes were identified in the human and monkey brains. Each receptor presented comparable distribution in the two primate brains. H1 and H2 receptors were particularly enriched in the caudate and putamen and observed in other brain areas such as the neocortex and hippocampus. H3-receptors were found to predominate in the basal ganglia where the highest densities were localized in the two segments of the globus pallidus. They were also observed in the hippocampus and cortical areas. The distribution of these 3 histamine receptors in the primate brain suggests the involvement of histaminergic mechanism in the functions of many brain areas. In particular, H2 and H3 receptors could play a role in the regulation of the basal ganglia functions in primates.