Purpose : To evaluate lung parenchymal change as seen on chest radiographs and high-resolution CT (HRCT) after the resolution of adenovirus pneumonia (a common cause of lower respiratory infection in infants and children), and the usefulness of HRCT during follow-up. Material & Methods : Four to 13(mean, 8) months after recovery, ten patients infected with adenovirus pneumonia underwent HRCT and chest radiographs. Eight were boys and two were girls, and their mean age was 26(range, 14-45) monthes. Adenovirus pneumonia had been confirmed by viral isolation in culture or serologic test. CT scanning was performed during quiet breathing ; collimation was 2mm and the interval from apex to diaphragm was 5-10mm. Lung settings were 1600 HU (window width) and -700 HU(level). CT findings were assessed and compared with chest radiographs by two chest radiologists, who reached a consensus. The patients were clinically followed up for one year. Result : On chest radiographs, hyperlucent lung was seen in 8 of 10 patients (80%) ; in one other there was partial collapse, and in one, findings were normal. The most common HRCT finding was a mosaic pattern of lung attenuation with decreased pulmonary vascularity in the area of lower attenuation ; this was seen in 8 of 10 patients (80%). Other findings were partial collapse, bronchiectasis, and bronchial wall thickening, each seen in two patients, and reticulonodular density, seen in one. In two patients HRCT findings were normal ; in one of these, chest findings were normal but a mosaic pattern of lung attenuation was found in all lobes. During follow-up, three patients wheezed continously. Conclusion : In cases of adenovirus pneumonia, HRCT demonstrated more specific parenchymal change than did chest radiographs ; area of a mosaic pattern of lung attenuation was seen, with decreased pulmonary vascularity in areas of lower attenuation ; bronchiectasis, bronchial wall thickening, and reticulo-nodular density were also noted. These findings were presumably due to bronchiolitis obliterans, a well known complication of adenovirus pneumonia, and are prognostically helpful.