An autoradiographical oxytocin (OXT) labeling procedure using frozen, unfixed tissue sections resulted in very dense labeling of the mammary gland. Binding sites for OXT were also found in various forebrain areas, including the hippocampus, especially the ventral subiculum and taenia tecta, central amygdala, posterior part of the anterior olfactory nucleus, claustrum, nucleus accumbens, bed nucleus of the stria terminalis, ventromedial hypothalamic nucleus, and the posterior pituitary. The ependyma of the lateral ventricle and/or the chorioid plexus near the lateral septum was labeled as well. These data support the hypothesis that OXT plays a role in a number of centrally regulated processes.