This is a report on four cases of the lobar emphysema due to proximal bronchial obstruction in the Department of Thoracic Surgery, Hanyang University Hospital, during the period of three and half years from 1972 to 1975. First case, a two years old male child was referred to our Department with the lobar emphysema of the lower lobe of the right lung with pneumonia. This emphysema was developed after aspiration of a piece of peanut. Bronchoscopy revealed that the bronchus of the right lower lobe was obstructed with the foreign body, however removal of the peanut through bronchoscope was not attempted because of corruption and softening of the peanut. The removal of the peanut by bronchotomy was performed after subsiding of acute phase of pulmonary infection. Postoperative course was uneventful and the emphysema was disappeared. Second case, a twenty months old female baby was referred to our Department with lobar emphysema of the lower lobe of the left lung. The emphysema was suddenly developed with coughing and dyspneic symptoms and the diagnosis was made roentgenologically. She gave a history of reccurrent infections of the respiratory tract after birth. Bronchoscopy showed an obstruction of the left main bronchus with the growing of fibrinous tissue on the bronchial mucosa. The protruded tissue in the left main bronchus taken out about O.8ml with biopsy forceps for histological examination. After this procedure, the emphysema of the left lung was disappeared. Histological finding was reported to be a chronic inflammatory granulation tissue. Third case, a two and half years old male child was referred to our Department with roentgenological lobar emphysema. Two weeks prior to admission he had an episode of sudden onset of coughing attack with dyspnea. Bronchoscopy revealed that the bronchus of the left lower lobe was obstructed with a mass which was strongly suspected of a neoplastic tissue. At operation, there was found a perforation of enlarged tuberculous lymph node in the bronchus of the left lower lobe and protrusion of granulation tissue into the bronchus. Ruptured orifice on themembranous wall of the left lower lobe bronchus was closed with interrupted suture after the" removal of a perforated tuberculous lymph node. Postoperative course was uneventful and antituberculous chemotherapy was given. Fourth case, a 47 years old man was admitted to our Department with the complaint of severe dyspnea of few months duration. Twenty years ago, he had a history of lung tuberculosis and was treated for many years. X-ray examination including tomography and bronchography revealed that the upper lobe of the right lung was destroyed with cavities, the lower lobe was completely shrunk, and the right middle lobe was strongly overdistended with narrowing bronchial trees. Differential bronchospirometry and lung scanning confirmed that the respiratory function of the affected lung was impaired almost totally. The value of the right lung was calculated on 6% of oxygen uptake, 1% of Minute volume, and 32% of vital capacity. The right pneumonectomy was performed under the careful consideration of anesthetic and surgical procedures. Postoperative course was uneventful and the respiratory function was improved nearly to the normal level.evel.