CML is a disease which progresses to blast crisis within five years of onset despite medical intervention. Allogeneic transplantation has provided a definitive cure for a large number of patients. The International Bone Marrow transplant registry reports a 67% three-year disease free survival for CML patients receiving a matched sibling transplant. However there remains a 17-20% treatment-related mortality and significant long-term complications. Myeloablative regimens with total body irradiation (TBI) are associated with certain sterility, along with a significant incidence of cataracts and second malignancies. Efforts to ameliorate this toxicity have led to the development of regimens lacking total body irradiation. Although the follow-up period for patients receiving these regimens has not been long enough to answer the question of long-term toxicity, it appears that the response rate and the disease free survival are comparable to regimens containing TBI. In addition, transplantation experience with aplastic anemia where TBI is not part of the regimen indicates that treatment related mortality along with the risk of long-term sequela are significantly decreased.