We report a case of endobronchial tuberculosis located in the main left bronchus suspected on a CT scan and assessed by fiberoptic bronchoscopy. This localisation is not unusual, and is often associated with a normal chest radiography. Air trapping present on high resolution CT scan led to focus the examination on proximal airways and to suspect their involvement. This observation underlines the value of expiratory CT scan in demonstrating proximal stenosis of main bronchi.