Glucagon therapy has been used to reverse severe hypoglycemia-induced unconsciousness, but no known study exists which reports its use during pregnancy. Pregnant diabetic women were eligible if they had either a prior hypoglycemic episode requiring intravenous glucose administration or had repeated capillary blood glucose determinations less than 40 mg/dl without any warning adrenergic symptoms. Of 51 insulin-dependent diabetic women, 16 were candidates for glucagon use during a recent 3œ-year period. Seven of these 16 persons required an injection on 12 occasions, and an immediate reversal of unconsciousness was encountered in 11 circumstances. No apparent short- or long-term maternal adverse effects were present. We conclude that glucagon therapy is needed infrequently for diabetic women during pregnancy but is helpful in reversing acute episodes of severe hypoglycemia.