Since Goldblatt and others have succeeded in producing hypertension in animals through the mechanism of renal ischemia there has been a revival of interest in the question of the renal factor in essential hypertension. Some writers on the subject have been inclined to disregard previous fundamental work concerning the background of hypertensive disease in human beings and to attribute all essential hypertension primarily to the operation of a renal mechanism. Others have attributed, in cases of essential hypertension, a primary etiologic role to a renal lesion which might have been coincidental. Hypertension occurs in approximately 15per cent of all persons and in probably a third of all persons more than 50 years of age; consequently, it could be expected that by chance alone there could be found a relatively high incidence of hypertension in any group of persons suffering from renal disease. Further-more, instances of long-standing renal disease can