Tracheobronchomegaly (also called Mounier-Kuhn syndrome) is a rare disease characterized by flaccid and markedly dilated trachea and main bronchi on inspiration with narrowing or collapse on expiration or cough. It is associated with recurrent lower respiratory tract infection. A 75-year-old man with unexpected giant tracheomegaly had a significant peritubal air leak which impeded an operation. Lumbar epidural anesthesia was performed for a subsequent operation without any sequela. Careful evaluation with chest radiography is basic to exclude a large airway. Chest computed tomography and fiber-optic bronchoscopy provided the diagnosis of a large airway. If a large airway is suspected, these examinations help to evaluate and manage the airway.