A recently developed 1-day screening procedure for angiotensinogenic ("high-renin") hypertension is based on (A) a fall in blood pressure in response to intravenous infusion of the angiotensin antagonist, saralasin (P-113), and (B) peripheral venous renin assays by radioimmunoassay, in a sodium-depleted state. Out of 700 hypertensive patients screened by these tests, 160 had renal imaging performed with technetium-99m glucoheptonate and iodine-131 Hippuran. The P-113 infusion test proved superior to peripheral venous renin assays for the detection of angiotensinogenic hypertension. Positive infusion tests correlated well with renal vein renin assays. Frequently, however, both these tests were positive with bilateral renal disease and/or malignant hypertension. While renal imaging proved valuable in indicating which patients had a unilateral abnormality, it frequently could not distinguish unilateral renovascular disease from unilateral parenchymal disease unrelated to angiotensinogenic hypertension. Twenty-five patients in this series had arteriographic renal artery stenosis, of whom 3 had false negative P-113 infusion tests, 9 had negative peripheral renin assays, and 3 had no imaging abnormalities. This study indicates that scintigraphy is a useful procedure for the investigation of hypertensive patients when the initial P-113 infusion test is positive, or discordant with other findings. By imaging, angiotensinogenic hypertension due to bilateral renal disease can be distinguished from unilateral renovascular disease, and the site of the ischemic renal tissue can usually be identified.