The presence of components of the renin-angiotensin system in ovaries and testes suggests that angiotensin II (All) is involved in gonadal function, and thus we sought to characterize receptors for All in rat and primate gonads. In the testes, autoradiographic studies showed receptors in the interstitium in all species. In rat interstitial cells fractionated by Percoll gradient, All receptors coincided with hCG receptors indicating that All receptors are located on the Leydig cells. In Leydig cells and membranes from rat and rhesus monkey prepuberal testes, All receptors were specific for All analogues and of high affinity (Kd = nM). During development, All receptor content in rat testes decreases with age parallel to a fall in the ratio of interstitial to tubular tissue. In the ovary, the distribution of All receptors was dependent on the stage of development, being high in the germinal epithelium and stromal tissue between five and 15 days, and becoming localized in secondary follicles in 20- and 40-day-old rats. No binding was found in primordial or primary follicles. In rhesus monkey ovary, All receptors were higher in stromal tissue and lower in granulosa and luteal cells of the follicles. Characterization of the binding in rat and monkey ovarian membranes showed a single class of sites with a Kd in the nmol/L range and specificity similar to that of the adrenal glomerulosa and testicular All receptors. Receptors for All were also present in membrane fractions from PMSG/hCG primed rat ovaries. Infusion of All (25 ng/min) or captopril (1.4 µg/min) during the PMSG/hCG induction period had no effect on ovarian weight or All receptor concentration in the ovaries. However, All infusion during PMSG treatment caused a 23% reduction in plasma progesterone and a 44% increase in estradiol. The presence of All receptors in the gonads together with components of the renin-angiotensin system lends further support for a role of All in ovarian and testicular function. Am J Hypertens 1989;2:395–402