Hyporeninemic hypoaldosteronism was observed in an infant at the age of 3 months. Persistent hyperkalemia, hyperchloremic acidosis and salt wasting were present. All abnormal electrolyte values were corrected by the administration of fludrocortisone. Both active and inactive renin were lowered. This infant had also an unexplained spastic quadriplegia and psychomotor retardation. Hyporeninemic hypoaldosteronism should be considered to be one of the causes of salt-losing in infancy.