Transient adrenal insufficiency in early infancy has been described by Jaudon.1Congenital hypoplasia as the cause of fatal adrenal failure is the least understood condition among the various etiological possibilities. The following study may be contributory to the understanding of the pathology of this rare condition and of the interrelation between the electrolyte-controlling mechanism and the histopathological changes of the adrenal cortex. Report of Case A white boy weighing 8 lb. 12 oz. at birth began vomiting, having diarrhea, and losing weight at the age of 2 weeks and was admitted to the hospital a week later in severe shock with diarrhea and dehydration. The skin was grayish, and the child appeared lethargic. The weight was 13 oz. below the birth weight. The genitalia were normal. A slight trace of albumin was found in the urine; tests for sugar and sediment were negative. Blood chemistry studies showed sodium, 120