A 38-year-old female with acute myelogenous leukemia (M2) received an allogeneic bone marrow graft from an HLA-DR one locus-mismatched sister during the first remission. The conditioning regimen consisted of busulfan and cyclophosphamide. Acute graft-versus-host disease (GVHD) developed on day 11 after transplantation. Although the GVHD was successfully treated with methylprednisolone, peripheral blood neutrophils that had begun to increase disappeared in association with improvement of the GVHD and graft rejection was eventually diagnosed. The second bone marrow transplantation from the same donor ended up with engraftment failure. She died of sepsis due to Candida albicans following the development of Epstein-Barr virus-associated B-lymphoproliferative disorder. The clinical course of this patient indicates that successful therapy of severe GVHD with methylprednisolone may lead to marrow graft rejection.