A 42-year-old woman was admitted with abnormal chest radiographs. Though interstitial pneumonia associated with dermatomyositis was diagnosed, her chest radiograph also revealed a narrowed trachea about 6 mm in diameter. Bronchoscopy showed that her trachea lacked a membranous posterior segment and O-shaped complete tracheal rings were present throughout the trachea, indicating congenital tracheal stenosis. Congenital tracheal stenosis is a rare disorder and is usually recognized in the first few weeks of life, but the patient had no history of dyspnea or recurrent pneumonia. This case suggests that among healthy people there are a very few who have asymptomatic congenital tracheal stenosis.