We describe two cases of fetal atrial flutter associated with severe fetal hydrops which were unresponsive to digoxin but were successfully treated with flecainide acetate. Two cases of fetal atrial flutter were identified in fetuses with severe fetal hydrops on 3rd trimester ultrasonogram(28 weeks' gestation and 30 weeks' gestation). Following failed digoxin monotherapy, flecainide acetate was added to digoxin. On the 7th day and 13th day after combined therapy, fetal heart rate converted to normal sinus rhythm without recurrence. Our cases showed that the combined therapy of digoxin and flecainide acetate can effectively treat fetal atrial flutter associated with fetal hydrops unresponsive to digoxin monotherapy.