Allogeneic bone marrow transplantation (BMT) is the only treatment modality that has consistently been demonstrated to cure patients with the myelodysplastic syndrome (MDS). Since the early 1980s, numerous publications have reported the results with BMT for over 700 patients with MDS and the lead patients are now disease-free for more than 16 years. Overall, these studies show that approximately 40% of patients are likely to be cured with allogeneic BMT. The best results have been reported for patients with refractory anemia who receive marrow from fully matched related donors, with 75% long-term disease-free survival rates. Factors that are associated with an increased risk of relapse and, thereby, shorter disease-free survival, include increased blast percentage and poor risk karyotype. Factors that are associated with an increased risk of non-relapse mortality and, in some studies, shorter disease-free survival, include longer disease duration, advanced patient age, therapy-related MDS, male patients, and use of mismatched or unrelated donors. However, favorable results have been seen in small studies of patients 55-66 years of age and in patients with refractory anemia undergoing matched unrelated donor BMT. Allogeneic BMT is appropriate therapy for patients with high or intermediate risk disease (risk category based on the International Prognostic Scoring System). The use of allogeneic BMT for patients with low risk disease is not well defined, but may be appropriate for particularly young individuals or those with a life-threatening single cytopenia.