Bronchiolitis obliterans (BO) is a late-onset noninfectious pulmonary complication that may occur 3 to 15 months following allogeneic hematopoietic stem cell transplantation (HSCT) [1, 2]. The incidence of BO following allogeneic HSCT is estimated at 1.7–19.4% [1–3] and the mortality rate varies from 14 to 100% [2]. While chronic graft-versus-host disease (GVHD) is thought to play an important role in the development of BO in the recipients, the other nonimmunologic factors, which include the conditioning regimen, viral pneumonitis and the use of immunosuppressive medications, are also potentially involved [1, 4]. Only 16–49% of BO patients showed improvement after administering immunosuppressive agents such as methylprednisolone, prednisolone, cyclosporine (CsA), tacrolimus, antithymocyte globulin and azathioprine [1, 2, 4]. At present, there is no established standard therapy for BO. We report a successful case of living-donor lobar lung transplantation (LDLLT) for therapy-resistant BO after allogeneic HSCT from the same donor. A 4-year-old boy was diagnosed as having B-cell precursor acute lymphoblastic leukemia. He was treated with combination chemotherapy and remained in complete remission after 2 years of chemotherapy. However, he developed a relapse 14 months after the completion of therapy, at age 7 years. He underwent bone marrow transplantation (BMT) from his HLA serotype-matched and blood type-matched mother at age 8 years. Genomic HLA typing was not performed. The conditioning regimen consisted of total body irradiation (12 Gy), etoposide (60 mg/kg), and cyclophosphamide (60 mg/kg 92). GVHD prophylaxis consisted of CsA and short-term methotrexate. Engraftment (absolute neutrophil count [500/ll) occurred on day 17. Acute grade IV GVHD, which affected the skin (stage 4) and liver (stage 1), developed on day 31. Treatment was initiated with prednisolone (1 mg/kg/day) in addition to CsA for 43 days with complete resolution of clinical GVHD. Chronic GVHD of the liver and gastrointestinal involvement evolved around day 180 and was confirmed by biopsy. Those symptoms improved with an increase in the CsA dosage. Around day 300, he began complaining of wheezing and dyspnea, which gradually worsened. Therefore, prednisolone (2 mg/ kg/day) was initiated in addition to CsA again, believing the cause was pulmonary GVHD. Thereafter, cyclosporine was replaced with tacrolimus on day 351 because he developed cyclosporine encephalopathy. He also developed several episodes of severe spontaneous pneumothorax, cutaneous and mediastinal emphysema and asthmatic attack requiring mechanical ventilation. Home oxygen therapy was started 2 years and 10 months after BMT. His respiratory distress continued to deteriorate and he developed hypercapnia resulting in respiratory failure 4 years and 7 months after BMT. A request for lung transplantation was raised by the family and the ethical problems were fully discussed. The patient (13 years old, height: 125 cm, weight: 16.4 kg) was considered a candidate for LDLLT, because he could not wait for a cadaveric lung graft, due to K. Oshima (&) A. Kikuchi S. Mochizuki R. Hanada Division of Hematology/Oncology, Saitama Children’s Medical Center, 2100 Magome, Iwatsuki-ku, Saitama 339-8551, Japan e-mail: oshima-k@umin.ac.jp