Three cases of placental chorioangiomas, from 6.5 to 10 cm in diameter, were diagnosed prenatally by ultrasound and color Doppler imaging at 21-34 weeks of gestation. In 1 case, due to fetal hydrops and maternal 'mirror syndrome', immediate delivery of a neonate, who was severely anemic, thrombocytopenic and had consumption coagulopathy, was required. In the other 2 pregnancies, conservative management was possible, once fetal cardiac failure and anemia were ruled out by the combination of fetal blood sampling and serial echographic and Doppler investigations.