A new syndrome, characterized by hypertrophy and hyperplasia of the juxtaglomerular apparatus of the kidneys, aldosteronism resulting from adrenal cortical hyperplasia, and persistently normal blood pressure is described in two patients. Overproduction of aldosterone could not be prevented by sodium loading or by administration of albumin intravenously; it was associated with hypokalemic alkalosis and Pitressin-resistant impairment of urinary concentrating ability. In both subjects, increased amounts of circulating angiotensin were demonstrated; infusion of angiotensin II produced rises of blood pressure in both subjects considerably less than the rises induced by comparable doses in normal subjects. The sequence of events, (1) primary resistance to the pressor action of angiotensin, (2) compensatory overproduction of renin and thus of angiotensin, and (3) stimulation of adrenal cortex by angiotensin is consistent with all the information available about the syndrome.