A radiographic hallmark in pulmonary agenesis is opacification of the ipsilateral hemithorax with displacement of the mediastinum in the direction of the agenetic lung. We believe this case report is the first in which the mediastinum was not displaced; instead, the liver and intact hemidiaphragm were displaced cephalad, preventing cardiac malposition. Contrast-enhanced computed tomography enabled us to diagnose this anomaly precisely.