One hundred sixteen patients underwent operation for renovascular hypertension from 1962 through 1975; 64% had aortorenal reconstruction and 36% had nephrectomy. Sixty-six percent were cured and 19% were improved. Rapid sequence intravenous pyelography, radioisotope renography, and renal arteriography were equal in ability to detect renovascular hypertension. Bilateral renal biopsy specimens had excellent prognostic value when performed in a graded semiquantitative manner. Plasma renin activity was the most consistently useful criterion for prediction of surgical cure if the following requirements were used: (1) elevated peripheral plasma renin activity, (2) elevated renin from the affected kidney, and (3) suppressed renin secretion from the contralateral kidney. An angiotensin II antagonist, saralasin acetate, used in six patients before operation in an attempt to identify those whose hypertension depended on angiotensin II activity, produced a depressor response correlating well with the surgical result.