Elevation of blood urea nitrogen in the hypertensive patient signifies a grave prognosis and a clinical problem for which medical management has been relatively ineffective. It has been demonstrated that renal failure in some of these patients may be the result of severely impaired renal blood flow produced by an extreme occlusive process localized in the main renal artery. Eight azotemic patients with extreme bilateral renal artery stenosis or marked unilateral renal artery narrowing with absence of the contralateral kidney survived operation directed toward restoration of normal circulation. Rapid improvement in renal function followed operation in each patient and hypertension was corrected or significantly reduced in all the patients.