A 38-year-old man was diagnosed as having acute myelogenous leukemia in December 2001. He achieved a complete remission after undergoing three courses of induction chemotherapy. As the patient's prognosis was considered to be poor, he was then treated with a bone marrow transplant from his HLA 1 antigen mismatched sister in May 2002. Grade 2 skin graft-versus-host-disease (GVHD) developed on day 14 but reduced with methylprednisolone (mPSL). Prednisolone (PSL) was discontinued on day 104, and the patient was discharged on day 112. There was no evidence of clinical chronic GVHD, the serum creatinine level remained high, and cyclosporine (CsA) was gradually tapered off and discontinued on day 165. However chronic GVHD of the skin appeared on day 179, and CsA (100 mg/day) was restarted. On day 186 he was admitted to our hospital complaining of fever. A CT scan of the chest demonstrated bilateral interstitial infiltrates, which were considered as lung GVHD lesions and PSL was started, following which chronic GVHD of the skin and liver improved. The lung GVHD worsened, however, subcutaneous and mediastinal emphysema developed and the patient died on day 206. Interstitial pneumonia had progressively worsened as the manifestation of the chronic lung GVHD. We concluded that this clinical course was rare.