Background: Giant Bullous Emphysematous (GBE) is developed from bullous lung parenchyma diseases and is resulted from multiple causes. The Images between GBE with pneumothorax are similar and dif cult to differentiate.Both are emergency cases that prompt diagnosis might mean proper treatment and life saving.This was a case study presenting a case of a 27-years-old-man to emergency room with dyspnoe. Respiratory rate of 32and coarse upper breath sounds with diminished breath sounds at the right lung. Chest Computed Tomography (Chest CT) and Chest X Ray (CXR) images at right lung has shown a large coalescing bulla which trapped air and  uid, compressed the adjacent lung parenchyma with resultant ipsilateral volume loss, air  uid level and thin walls. Smaller bullous lesions were also seen in the left upper lobe. Results: the difference characteristics between chest CT and CXR GBE compared to pneumothorax were: 1) the location of lesions: GBE was within the lung and pneumothorax was in pleural space; 2). The shape of the lesions: GBE, oval, thin walled-less than 1 mm may be formed by pleura, septa or compressed lung tissue. Pneumothorax: with linear density outlining distinct lucent area with broncho vascular marking 3.) Complications: GBE caused minimal mediastinal shifts line and spontaneous pneumothorax. Pneumothorax with large areas caused greater mediastinal shift line. Conclusions: chest CT and CXR were important to determine between GBE and pneumothorax based on the location, the shape of the lesions and complications.