A large intrapericardial mass was incidentally found in a fetus at 32 weeks gestational age, which was accompanied by a significant pericardial effusion. The baby was delivered by cesarean section and had surgical removal of the tumor on the second day of life. Alpha-fetoprotein was elevated. The pathologic analysis demonstrated a grade I immature teratoma with foci of hepatoid tissue. The patient had an uneventful postoperative recovery. A review of the literature and pathologic implications are discussed.