In summary, there is now considerable evidence for an interaction between the renal sympathetic nerves and the baroreceptor and macula densa mechanisms in the control of renin secretion rate. Renal sympathetic nerve activity varies from minute to minute throughout the day. At times, increases in renal sympathetic nerve activity sufficient to cause a direct neural release of renin from juxtaglomerular cells may occur. Under other circumstances, changes in renal sympathetic nerve activity may be more modest, but still sufficient to modulate the renin secretion rate responses mediated by other mechanisms. The studies reviewed show that prevailing renal sympathetic nerve activity can modulate the magnitude of the renin secretion rate response to stimulation of the renal vascular baroreceptor and the tubular macula densa receptor mechanisms. The degree of interaction between the neural and non-neural mechanisms is dependent on the level of activation of the non-neural mechanisms and the intensity of renal sympathetic nerve activity.