The response of idiopathic spontaneous hypoglycemia of infancy and childhood to therapy is variable. There is no single therapeutic agent which will uniformly maintain blood sugar concentration in the normal range in these patients. It has been suggested that a long-acting glucagon preparation may be of value when idiopathic spontaneous hypoglycemia is refractory to control by diet, corticosteroids, ACTH, ephedrine, or various combinations of these agents. It is the purpose of this paper to report our experiences with glucagon in maintaining the blood sugar concentration of a patient with idiopathic spontaneous hypoglycemia. Case Report History and Physical Examination: A 6-month-old Mexican-American boy was evaluated for convulsions which had begun at 2½ months of age.