Giant fetal neck masses can cause airway obstructions with potentially poor fetal prognoses after delivery. The relationship between the fetal neck mass and the airway structure can be evaluated prenatally with ultrasound and magnetic resonance imaging (MRI). The ex utero intrapartum treatment (EXIT) procedure can be used to obtain a fetal airway while fetomaternal circulation is preserved. We present a case in which a giant mass in the fetal neck was diagnosed prenatally at time of ultrasound and MRI examination and a successful EXIT procedure was carried out. The 30-year-old woman (gravida 1, para 0) had been referred to this institution in her 26th week of gestation. We diagnosed the mass as a giant fetal cervical lymphangioma (9.0×7.7 cm) based on the ultrasound and MRI findings. The EXIT procedure was performed at 37 weeks of gestation, and the airway was successfully secured. The baby was female and weighed 3,145 grams. Arterial cord blood gas value was pH 7.233; PCO2, 65.3 mm Hg; PO2, 6.2 mm Hg; BE, minus;2 mmol/L. The baby had a giant neck mass the size of a soft ball. The tumor was pathologically diagnosed as a lymphangioma. The postpartum clinical course has been good since the EXIT procedure.