The postpneumonectomy syndrome is a rare complication occurring after right pneumonectomy and is seen mainly after pneumonectomy in childhood. The presenting symptoms are dyspnea, stridor, and recurrent pulmonary infections. The syndrome is caused by the shifting and rotation of the heart and mediastinum into the right hemithorax, and anterior herniation of the left lung. This causes tortuosity and stretching of the trachea and compression of the left main bronchus and left lower lobe bronchus, eventually resulting in secondary tracheobronchomalacia. This report reviews two cases of postpneumonectomy syndrome following pneumonectomy in adulthood. After implantation of an expandable prosthesis, an anatomic correction of the shifted mediastinum was achieved, which in both cases resulted in instantaneous and sustained relief.