A 22-year-old man was referred due to symptoms of dyspnea and chest pain. Chest radiography revealed large lucency in the right hemithorax with contralateral mediastinal shift (Picture 1). Chest CT showed a hyper-lucent, hyperextended right lower lung (Picture 2). Spirometry showed forced expiratory volume (FEV)1/forced vital capacity (FVC) 80.4%, FVC (Pred) 1.99 L (40%), FEV1 1.6 L. Lung perfusion/ventilation scan showed a large non-segmental V/ Q matched defect. He received volume reduction therapy. Microscopic sections showed irregular large cystic spaces lined with bronchiolar epithelium, and bronchiole-like structures with a fibromuscular core (Picture 3). The patient was diagnosed with congenital lobar emphysema. Dyspnea improved after surgery and follow-up spirometry showed FEV 1/FVC 83.3%, FVC (Pred) 2.63 L (52%), FEV1 2.19 L.Congenital lobar emphysema is uncommon and characterized by an over-distension of a histologically normal lung. It is caused by obstruction of the developing airway, thus leading to air trapping through a "ball-valve" mechanism. This condition usually presents within the first month of life, but is rare after 6 months of age (1). The left upper lobe is the most frequently affected lobe. Surgical resection of the affected lobes is appropriate for symptomatic patients (2).