Adrenal cortical disease, especially adrenal insufficiency, is far more frequent than adrenal medullary disease and often goes unrecognized for extended periods. Physicians caring for children should consider the diagnosis of adrenal insufficiency in any patient with unexplained hypoglycemia, growth failure, weight loss, vomiting, or lethargy. These nonspecific signs and symptoms may be mistaken for, and should be differentiated from, infection, malnutrition, gastrointestinal disease, inborn errors of metabolism, anorexia, chronic fatigue syndrome, and depression.