A growing body of evidence suggests that angiotensin may have a functional role in growth and development, in addition to its classical role in the maintenance of body water homeostasis. Components of the renin-angiotensin system have been identified in the rat fetus. Because of the association between the renin-angiotensin system and hypertension, we quantified angiotensin receptor binding sites in the brains of spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) rats during perinatal development. Using in vitro receptor autoradiography we identified specific 125I-Sar1,Ile8 AII binding in several areas of the brains of perinatal rats of both strains and observed significant differences in the concentration of binding sites, at different ages in several brain nuclei. With the knowledge that components of the renin-angiotensin system appear early in development and are known to have an association with cellular growth, it is possible that an irregularity in this system occurring during neurogenesis could contribute to developmental abnormalities, as well as subsequent hypertension.