Only 5 reports of cases of renal arteriovenous fistula appeared before or in 1953. Subsequently, 7 isolated reports brought the total to 12, and the 3 that we are reporting make 15. In reviewing the subject, the classification, incidence, causation, clinical features, diagnostic procedures, and pathophysiologic features were considered. Good evidence supports the thesis that in cases of congenital arteriovenous fistula an eroding renal arterial aneurysm is etiologic. Outstanding clinical features were hypertension (to group 4) and myocardial insufficiency; these contrast markedly with features of the usual peripheral arteriovenous fistula. Dramatic relief of heart failure and lowered reserve followed corrective operation in every case in which these features were recorded; relief of hypertension followed corrective operation in 11 of 12 cases in which this feature was mentioned. A loud, diffuse, continuous bruit invariably was present. Preoperative and postoperative catheterization and indicator-dilution studies, angiograms and aortograms are diagnostic measures emphasized in our 3 cases. Arterialization of blood in the vena cava, greatly increased cardiac output, and markedly shortened recirculation times of the dye were found. Excretory urograms were abnormal in 11 of the 12 cases in which they were made. The mechanism producing hypertension appears related to loss of pressure, decrease in flow, and loss of pulsatile character in the renal artery distal to the fistula, giving a Goldblatt-kidney type of end result. A vicious cycle of increasing hypertension followed by increasing flow through the shunt makes heart failure inevitable. Since 10 of the 15 cases were reported in the last 4 years, indicating that the lesion is commoner than previously supposed, we advise auscultation over the renal regions in patients with cardiac enlargement or failure of unknown causation, unexplained deformities in urograms, and renal tumors.