We characterized the influence of high pressure and low pressure intra vascular receptors on renal nerve activity in the pentobarbital sodium-anesthetized nonhuman primate Macaca fascicu- laris. Epinephrine-induced increases in arterial pressure were used to stimulate high pressure recep- tors, and intravascular volume expansion was used to stimulate both high and low pressure receptors. In addition, the intravascular mechanoreceptors were stimulated directly by intravenous veratrine administration. All interventions produced large decreases in renal nerve activity in the intact state. Denervation of the carotid sinus or bilateral cervical vagal section diminished, whereas sino-aortic denervation with vagotomy completely abolished all responses of renal nerve activity to these inter- ventions. We conclude that the nonhuman primate possesses very sensitive renal nerve sympathetic reflexes that are modulated by intravascular mechanoreceptors whose afferents traverse the carotid sinus nerves and the vago-aortic trunks. The carotid sinus nerves and the vago-aortic trunks appear to be equally effective in inhibiting renal nerve activity in response to increases in arterial pressure. In addition, there are no afferent pathways mediating intravascular mechanoreceptor modulation of renal nerve activity outside the carotid sinus nerves and the vago-aortic trunks. Circ Res 46: 726-730, 1980