BACKGROUND: In acute aortic dissection, various findings can be found in computed tomography. However, pulmonary infiltration is rarely observed. CASE REPORT: A 57-year-old man was diagnosed with acute aortic dissection (AAD), but had marked infiltration shadows in his right lung. Intraoperative findings showed that large subadventitial hematomas had spread from the ascending aorta to the right pulmonary artery, which may have caused the infiltration of the lung. CONCLUSIONS: Subadventitial hematoma must be considered in rare cases of AAD with pulmonary infiltration.