Seventy-five patients with renal artery stenosis were studied; 50 patients had unilateral lesions and 25 had bilateral lesions. Divided renal vein renins and peripheral renins were collected under strict salt intake, drug intake, and postural conditions. Divided renal vein renin ratios and a scoring system that included peripheral renin and affected and contralateral renal secretion of renin were applied to each patient and compared in each to the patient's ultimate surgical result. Both methods, if positive, are highly predictive of cure in patients with renal artery disease. Both methods are plagued by significant false-negative rates, 20% for renal vein ratio, 33% for the scoring system in patients with unilateral stenosis, and 35% and 48%, respectively, in patients with bilateral renal artery stenosis. For these reasons, surgical selection should be based on evaluation of a combination of the clinical presentation, angiographic findings, and renin data.