Cerebral edema complicating treatment of diabetic ketoacidosis does not seen to be very rare. This neurologic complication, which was observed in 3 cases, presents similarly in all patients, occurs mainly in children and adolescents and is usually lethal. Its mechanism has not been clearly explained yet. Various etiologic factors have been considered; sodium depletion, rapid infusion of hypotonic solutions and rapid fall of plasma glucose level might have a deleterious effect. On the basis of these data, some preventive therapeutic measures are proposed.