[en] Serotonin-1A receptors were visualized and their anatomical distribution mapped within the monkey and the human hippocampus by using in vitro receptor autoradiography of the selective agonist (³H)8-OH-N, N-dipropyl-2-aminotetralin ((³H)8-OH-DPAT). The results show high densities of serotonin-1A receptors hetergeneously distributed in different subfields and layers of the monkey and the human hippocampal region. High densities are found in the molecular layer of area dentata, all layers of regio superior and the subiculum, parasubiculum, and layers 2, and 4 through 6 of the entorhinal area. In the human hippocampus, a distinct band of (³H)8-OH-DPAT binding sites is present in the subgranular zone of the area dentata. The similar anatomical distribution of (³H)8-OH-DPAT binding sites in the monkey and the human hippocampal region suggests that the serotonin-1A receptor is phylogenetically well preserved and indicates that this receptor may mediate action(s) of serotonin in the primate, including the human hippocampal region. (author)