Case 1: A 26-year-old female was admitted because of leukocytosis with 43.6% myeloblasts and 33.6% monocytes, and trilineage myelodysplasia (T-MDS) was detected on bone marrow (BM) smear. She was diagnosed as having acute myeloid leukemia (AML) (M4) with T-MDS and was treated with the Japan Adult Leukemia Study Group (JALSG) AML87 protocol. After completion of chemotherapy, leukemic myeloblasts remained minimally and myelodysplastic changes were still detected on BM smear. She underwent allo-BMT from an HLA-identical sibling. The conditioning regimen consisted of busulfan and cyclophosphamide. Cyclosporine A and short term methotrexate were administered prophylactically for graft-versus-host disease (GVHD). She developed slight veno-occlusive disease and pancytopenia, which improved soon. She is surviving free of disease for 37 months from BMT. Case 2: A 41-year-old male was diagnosed as having T-MDS AML (M2) and achieved complete remission with the AML89 protocol, but relapsed soon. He underwent allo-BMT from an HLA-identical sibling. The conditioning regimen and prophylaxis against GVHD were the same as in case 1. He developed mild acute GVHD, pleural effusion and later mild chronic GVHD. These improved soon. He is surviving free of disease for 21 months from BMT. Some reports suggest that intensive chemotherapy can induce CR in 40%-70% of patients with T-MDS AML, but most of them tend to relapse and rarely survive long. We consider that the best strategy for treatment of T-MDS AML is allo-BMT at present, if suitable donors are available.