PURPOSE: The purpose of this study was to evaluate the high-resolution CT features of Swyer-James syndrome with special attention to the airway lesions and to determine the clinical utility of high-resolution CT compared with that of chest radiography. MATERIALS AND METHODS: In seven patients with Swyer-James syndrome, we retrospectively reviewed chest radiographs obtained during inspiration and expiration and high-resolution CT scans obtained in inspiration. The high-resolution CT appearance was evaluated and compared with that of chest radiography. RESULTS: On both chest radiographs and high-resolution CT, the affected lung volume was relatively diminished in four patients and normal in three patients. In all seven patients, chest readiographs showed hyperlucency of the lung which was unilateral in four and bilateral in three patients. Unilateral small hilum was seen in six patients and bronchiectasis was demonstrated in one patient on chest radiographs. The hyperlucent lung volume was not diminished on expiratory radiographs in all seven patients. In all patients, high-resolution CT demonstrated low attenuation regions of the lung either bilaterally(n=5) or unilaterally(n=2). Pulmonary vessels were markedly decreased in size and number in the lung parenchyma with low attenuation. Six patients had bronchiectasis on high-resolution CT, which were cylindrical or varicose in five and cystic in one. Bronchiolectasis was observed in three patients on high-resolution CT. CONCLUSION: The high-resolution CT findings are characteristic of Swyer-James syndrome. High-resolution CT is more sensitive than chest radiography in detecting regions of low attenuation and bronchiectasis and may be useful for the diagnosis of Swyer-James syndrome. Our results suggest that bronchiectasis is a frequently associated airway lesion of Swyer-James syndrome and bronchiolectasis may be associated in some cases.