Ovarian cysts are frequent findings in fetuses and neonates, and their optimal therapy is not yet properly established. We report the finding of a fetal thecalutein ovarian cyst (6.6 x 5.3 cm) diagnosed prenataly through sonography. Pregnancy was interrupted by cesarean section during 38th gestation week. Ovarian cyst was removed twelve hours after cesarean section (laparotomy). Patient evolution was satisfactory. Literature was reviewed. When ovarian cyst is higher than 5 cm and non-complicated, surgical therapy in an option.