Congenital tracheal stenosis (CTS) is a rare disorder almost always diagnosed in infancy due to respiratory failure and other cardiopulmonary abnormalities. We experienced a 42-year-old female undiagnosed with CTS until difficult intubation upon surgery. Chest X-ray and computed tomography (CT) images revealed bronchial narrowing, which could already be seen prior to intubation, but was left unnoticed. Difficult airway management is a potentially lethal airway emergency. This life-threatening situation is preventable with the appropriate awareness. We report this clinically valuable case for the safety of future patient care. In English and Japanese literature, there are only 12 reported cases of CTS diagnosed in the adult. Ours and six previous cases were discovered with difficult intubation, a preventable life-threatening airway emergency. Pre-intubation images should be examined carefully for the possibility of CTS, as its frequency may be underestimated. Moreover, in treatment resistant recurrent asthmatic episodes, CTS should be kept in mind.