A fetal sublingual cystic lesion was diagnosed by routine prenatal ultrasonograpby at 21 weeks of gestation and followed tip until term in a tertiary care center. Fetal growth was normal as was the amniotic fluid volume. Ex utero intrapartum treatment was Performed and the cyst was aspirated to allow breathing and swallowing during planned Cesarean section. The cyst was totally excised when the newborn was 2 7 days of age and histological examination revealed a mucous cyst of the mouth floor. Copyright (C) 2003 ISUOG. Published by John Wiley Sons, Ltd.