High-resolution computed tomography (CT) was performed in 20 patients with diffuse panbronchiolitis. Images of abnormal peripheral lung were classified into four types: small nodules around the end of bronchovascular branchings (CT type I), small nodules in the centrilobular area connected with small branching linear opacities (CT type II), nodules accompanied by ring-shaped or small ductal opacities connected to proximal bronchovascular bundles (CT type III), large cystic opacities accompanied by dilated proximal bronchi (CT type IV). CT classifications were compared with radiographic classifications and clinical stages of the disease. The comparison revealed that the classification based on CT findings reflected the clinical stages and pathologic process of diffuse panbronchiolitis. The authors conclude that high-resolution CT is useful in the evaluation of both the location and severity of the lesions.