OBJECTIVE To evaluate the value of X-ray and spiral computed tomography (SCT) in the diagnosis of Swyer-James syndrome (SJS). METHODS A total of 28 patients, 12 males and 16 females, were studied retrospectively. Ages ranged from 11 to 57 years, the mean age was 32 years. All patients underwent inspiratory chest X-ray films, 5 with expiratory chest films and 1 with bronchogram. Furthermore, inspiratory and expiratory SCT scans were performed. The SCT findings were analyzed and compared with X-ray films. RESULTS SCT demonstrated 56 lobes with hyperlucency and diminished vascularity. The size of 51 lobes were smaller and 5 were normal. X-ray films showed that hyperlucency was only in 29 lobes, in which 19 lobes were small-sized and the other 10 lobes normal. There were 56 lobes with air-trapping on expiratory SCT scans, but only 5 lobes with air-trapping on expiratory X-ray films. Bronchogram in 1 case demonstrated bronchiectasis and bronchiolitis obliterans. SCT showed 24 patients with bronchiectasis, 9 patients with tuberculosis, 10 patients with bronchiolitis, and 2 with segmental collapse. CONCLUSIONS SCT scan is superior to chest radiography in the diagnosis and differential diagnosis of SJS.