We describe a giant bilateral vascular mass in the skin of the chest diagnosed by ultrasound investigation in a fetus of 20 gestational weeks. Ultrasound and colour Doppler investigations detected no signs of early congestive heart failure but rapid and excessive enlargement of the vascular mass. Indications of increased fetal blood volume were found. The fetus had additional minor anomalies. Early in utero manifestation suggests a severe vascular malformation.