We used quantitative autoradiography to localize thyrotropin releasing hormone (TRH) receptors in human brain. Highest concentrations of TRH receptors were localized within the cortical, basal, and lateral nuclei of the amygdala and the molecular layer of the hippocampus. Low levels were found in the cortex, diencephalon, and basal ganglia. The radioligand bound with similar affinity and pharmacology to pituitary gland as to brain. These data suggest that authentic TRH receptors in the hippocampus and amygdala may mediate the putative effects of TRH on the human brain.