We report an extremely rare case of an unruptured non-communicating rudimentary horn full-term pregnancy. A woman who had a uterine malformation was misdiagnosed as uterus didelphys and gave birth to a live, healthy fetus. The correct diagnosis was not made until cesarean section at 37 4/7 weeks. The case suggests that women who are pregnant in a rudimentary horn could obtain a full-term delivery and give birth to a live and healthy baby.