Long-term survival has become achievable after bone-marrow transplantation, but various pulmonary diseases due to chronic graft-vs.-host disease have been recognized. Particularly, bronchiolitis obliterans is a life-threatening complication with no effective remedy. Bilateral pneumothorax associated with bronchiolitis obliterans is rare, but it requires careful attention. In a 42-year old man with intractable pneumothorax after bone marrow transplantation and surgical procedures, extensive thoracolysis was effective as an acute treatment for this disease.