<p><b>OBJECTIVE</b>The beta-thalassemia major is a common hereditary hematology disease in southern China. The combination of blood transfusion and iron chelation is now the reference treatment. The allogeneic hematopoietic stem cell transplantation is the only curative therapy for beta-thalassemia major. In this study the investigators observed and evaluated the effects of umbilical cord blood transplantation (UCBT) for patients with beta-thalassemia major.</p><p><b>METHODS</b>Twelve cases of beta-thalassemia major aged from 1.3 to 8.3 years (8 male and 4 female) received UCBT. Eleven of the twelve donors were siblings and one was unrelative. Eight patients received no antigen and four patients received two antigen disparate grafts. According to the Pesaro's classification for thalassemia, 10 patients were at grade I or II, and 2 were at grade III. The HLA-identical patients accepted the conditioning regimen consisting of busulfan, cyclophosphamide and antithymocyteglobulin. The HLA-mismatched patients accepted the conditioning regimen consisting of hypertransfusions, continuous iv desferrioxamine, hydroxyurea, fludarabine, busulfan, cyclophosphamide and antithymocyteglobulin. The harvest stem cells contained 3.63 - 16.0 x 10(7)/kg of nucleated cells, 0.11 - 1.03 x 10(6)/kg of CD(34)(+) cells and 0.17 - 1.18 x 10(5)/kg of colony-forming-unit-granulocyte macrophages. Cyclosporine alone or in combination with mycophenolate mofetil (MMF) was given for acute graft-versus-host disease (aGVHD) prophylaxis.</p><p><b>RESULTS</b>Of the 12 patients, 10 were engrafted. Ten patients had neutrophil recovery (> 0.5 x 10(9)/L) and seven patients had platelet recovery (> 50 x 10(9)/L). The median time was 18.1 and 57.3 days, respectively. Seven patients had disease-free survival (DFS) at a median follow up of 23 months (range 4 - 63 months). Three patients had rejection and autologous hematopoitic reconstitution. Two patients were not engrafted. One patient acquired severe aplastic anemia, another patient died of severe infection. The incidences of grade I and grade II aGVHD were 60% (6/10) and 40% (4/10), respectively. There were no long-term complications in the disease free survivors.</p><p><b>CONCLUSIONS</b>Grade I-II beta-thalassemia major patients receiving sibling UCBT had high DFS. UCBT is an effective way to treat beta-thalassemia major.</p>