Batter's syndrome is characterized by retardation in growth pitressin-resistant hypostenuria, hypokalemic alkalosis, high activity of the jux angiotensin-renine-aldosterone system with normal blood pressure; vascular insensibility to angiotensin and hypertrophy and hyperplasia of the juxtaglomerular apparatus. In both patients we studied, we found negative balance of sodium and potassium conditioned to a renal loss of them.