Angiotensin II-amide administered intravenously at 0.2 µg/kg·min together with isotonic saline to rats with either DCA-induced or renal hypertension had the same diuretic and natriuretic effects as in normal rats. In renal hypertension (induced by a clip on one renal artery leaving the other kidney untouched) the normal overall diuretic response appeared to be due to the clamped kidney only. In the unclamped kidney of renal hypertensive rats the tubular diuretic and natriuretic response to angiotensin was abolished. Hydrochlorothiazide (5 mg/kg i.v., followed by 1 mg/kg •min) also failed to elicit its normal natriuretic response in the unclamped kidney. This failure, apparently, was the consequence of a greater depression of GFR (C<sub>In</sub>) in the unclamped kidney.