We describe a case of congenital cystic adenomatoid malformation treated by thoracoamniotic shunting using a double-flower catheter. An ultrasound examination at 25 weeks' gestation revealed a cystic mass within the fetal thoracic cavity, hydrops and polyhydramnios. Thoracoamniotic shunting under ultrasound guidance using a double-flower catheter was performed at 27 weeks. The procedure not only decompressed the lung cyst but also improved the secondary physiological changes, i.e. mediastinal shift, hydrops and polyhydramnios. A 2438-g male neonate was delivered at 37 weeks with no respiratory problems and resection of the right lower pulmonary lobe was successfully performed 24 h after birth.