Cerebroventricular administration of angiotensin II elevated arterial pressure and reduced plasma renin activity (PRA) in renal venous blood in anesthetized cats. Further, there was an increase in the concentration of urinary sodium, as well as the rate of Na⁺ excretion. Acute renal denervation significantly reduced the effects of central angiotensin II on the PRA and on the natriuresis. The data suggested involvement of a neurogenic component in these effects. Further, it appears that there may be a reciprocal relationship between CSF renin activity and PRA.