Renal and metabolic studies were performed on a 4-year-old Negro girl with dwarfism, polyuria, polydipsia, salt craving, hyposthenuria, and hypokalemic alkalosis. Hypertrophy and hyperplasia of the juxtaglomerular apparatus were seen on renal biopsy. The aldosterone secretion was elevated. The serum renin concentration was unusually high and an inadequate elevation of blood pressure occurred in response to infusions of angiotensin, vasopressin, and levarterenol. Treatment with potassium salts, spironolactone, and liberal salt intake for a period of six years improved the hypokalemia and dwarfism in this girl.