We experienced a case of cervico-mediastinal bronchogenic cyst in which a c
ervical cystic mass was detected by prenatal ultrasonography. On prenatal u
ltrasound, a unilocular, well-defined and hypoechoic mass was detected in t
he fetal neck. The baby was born by a normal vaginal delivery at 40 weeks o
f gestation, and had no respiratory distress. Radiological investigations d
emonstrated a cyst in the cervico-mediastinal region, which displaced the t
rachea to the left. At the age of 32 days, an elective resection was easily
performed through a right inferior collar incision after first aspirating
the contents of the cyst. Prenatal sonography showing abnormal findings is
effective for identifying cysts in the perinatal period and allows for the
timely resection of such cysts before respiratory distress occurs.