In healthy adults, diagnosis of aspiration of foreign body into tracheobronchial tree is not difficult because various symptoms such as dyspnea, coughing, or cyanosis develop when foreign b~y is aspirated into tracheobronchial tree. But unless a clear history of an aspiration event can be obtained diagnosis will be delayed. Early complications of tracheobronchial foreign body aspiration include asphyxia, cardiac arrest, dyspnea, laryngeal edema, and cyanosis. Late complications include pneumonia, lung abscess, bronchiectasis, hemoptysis, bronchial stenosis, arid polyp. Treatment is removal of foreign body by operation or bronchoscopy. Currently, flexible bronchoscopy is preferred in adults than rigid bronchoscopy. A 36-year-old male visited to Dongkang hospital due to productive coughing and dyspnea On auscultation, focal inspiratory wheezing was heard. On chest PA, mild emphysematous change was seen. Flexible bronchoscopy was done. Bronchoscopically, mucoid impaction, surrounding inflammation, foreign body lodged in the right lower lobe bronchus, and interbronchial fistula(between right middle and lower lobe bronchus) were seen Foreign body(2.4 x 1.3cm sized antacid package) was removed by flexible bronchoscopy. Later, history of aspiration of a piece of antacid package was found. We report a case of recurrent bronchitis with interbronchial fistula as a result of occult aspiration of foreign body with review of the literatures.