Cryostat sections of the central nervous system of adrenalectomized male rats injected with [3H]corticosterone were examined by radioautography. One hour after the injection, radioactivity was found to be selectively concentrated in specific neurons of the septum, the hippocampal complex (precommissural hippocampus, cornu Ammonis, gyrus dentatus, subiculum), the indusium griseum, the amygdala and in certain areas of the cortex. In the hippocampus, the pyramidal neurons in fields CA1 and CA2 of the cornu Ammonis and the granule neurons of the gyrus dentatus contained more radioactivity than did other regions of the brain. Most of the silver grains were localized in the nuclei of labeled cells. The topographic distribution of corticosterone-concentrating neurons shows that the hormonal target sites in the central nervous system are mainly extrahypothalamic.