Patients with class 3 thalassemia (liver edge greater than 2 cm below costal margin, a history of inconsistent chelation, and portal fibrosis) receive a less intensive conditioning regimen consisting of oral busulfan every 6 hours on days -7 to -4; anti-thymocyte globulin IV on days -5 to -1 and days 1-5; cyclophosphamide IV on days -3 to -2; and allogeneic BMT on day 0.