A 34-year-old woman with chronic myeloid leukemia underwent allogeneic bone marrow transplantation (BMT) after receiving high-dose chemotherapy and total body irradiation. She experienced progressively dry cough 51 days after BMT, and chest X-ray films showed patchy infiltrations in the lower fields of both lungs on the 66th day after BMT. The symptoms of cough, fever, and hypoxemia worsened. The patchy infiltrations continued to spread and fuse. Diffuse alveolar hemorrhage (DAH) was diagnosed on the basis of high-resolution CT and bronchoalveolar lavage findings. Treatment with high-dose methyl prednisolone pulse therapy, antibiotics, and haptoglobin resolved the patient's DAH symptoms. DAH was thought to be secondary to thrombotic microangiopathy. The majority of patients who experience DAH after BMT eventually die. The remission observed in our case was rare, and illustrated that steroid therapy can be effective for DAH after BMT.