We report our experience in successful unrelated-donor bone marrow transplantation in 2 cases of beta-thalassemia major, which are approved to be the first 2 cases in Asia. The 2 children receiving transplantation of the bone marrow from unrelated donors were diagnosed as having beta-thalassemia major, whose gene mutation type was homozygous and double heterozygote. High-resolution HLA typing found a mismatch with 1 sub-locus in both cases, and red blood cell type was mismatched in 1 case. Pretransplant conditioning protocol contained busulfan (BU, 16 mg/kg x b.w.), cyclosphamide (CY, 200 mg/kg x b.w.), anti-thymocyte globulin (ATG, 90 mg/kg x b.w.) and fludarabine (25 mg x d-1 x m-2). To prevent graft-versus-host disease (GVHD) episodes, cyclosporine-A (Cs-A) and methotrexate (MTX) were administered. The 2 cases experienced condition resembling serum sickness during pretransplant conditioning. After bone marrow transplantation, 1 case had grade acute GVHD in the skin, another developed grade acute GVHD in both the skin and intestinal tract, but the condition was brought under control in both cases after proper treatment. The time for peripheral neutrophil granulocyte recovery to above 0.5 x 10(9)/L was 19 and 16 days postoperatively, respectively, and the time of WBC recovery to normal was 54 and 80 days postoperatively. Platelet recovery to over 50 x 10(9)/L occurred on postoperative days 61 and 90, and Hb recovered to above 100 g/L in both case on days 110 and 83 respectively. The time of final blood transfusion was 53 and 62 days postoperatively for the 2 patients. Gene mutation type in the 2 cases was switched to normal of the donors. After retrieval of relative literature, the 2 cases were approved as the first 2 successful unrelated-donor bone marrow transplantation cases in Asia. This will provide a new possibility of donor supply for hematopoietic stem cells transplantation in thalassemia.