We report a case of bilateral pulmonary agenesis (BPA), which was suspected during a prenatal US examination and diagnosed by fetal magnetic resonance imaging (MRI). BPA is an extremely rare congenital anomaly and, although many fetal structural defects can be detected with a high degree of confidence after introducing high-resolution US, the prenatal diagnosis of BPA remains problematic. Other thoracic abnormalities, such as a congenital diaphragmatic hernia, congenital cystic adenomatoid malformation, and pulmonary sequestration, should be excluded from the list of possible diagnoses before coming to the conclusion of BPA, because BPA is absolutely incompatible with extrauterine life, and an accurate internal diagnosis can prevent a futile intervention from being performed.