We report a case of pulmonary veno-occlusive disease (PVOD) following allogeneic bone marrow transplantation (BMT) for the treatment of acute myeloid leukemia (AML) from an HLA mismatched mother using a reduced-intensity conditioning (RIC) regimen including gemtuzumab ozogamicin. The patient was a 21-year-old male who complained of dyspnea with hypoxemia followed by loss of consciousness. The abnormalities in chest CT and echocardiography were compatible with a diagnosis of PVOD. Treatment with 1 mg/kg of oral prednisolone resolved dyspnea and hypoxemia within a few days, and chest CT abnormalities disappeared in a week. This report is the first to describe PVOD following RIC stem cell transplantation.