Myelodysplastic syndromes (MDS) are hemopoietic stem cell disorders, and hemopoietic stem cell transplantation is currently the only therapeutic modality with curative potential. Among patients with less advanced/low-risk MDS (<5% marrow blasts), 3-year survivals of 65?70% are achievable with HLA-identical related and unrelated donors. The overall probability of disease recurrence in these patients is <5%. Among patients with more advanced disease (5% marrow blasts), the relapse probability is higher, ranging from 10?40%, and relapse-free survival is correspondingly lower. The criteria proposed by the International Prognostic Scoring System, derived from non-transplanted patients, also predict survival following transplantation. The development of reduced-intensity conditioning regimens and modification of conventional regimens, all aimed at optimizing the transplant approach, have permitted successful hemopoietic stem cell transplants even in patients 60?70 years of age. Improved survival with transplants from unrelated volunteer donors reflects to a large extent selection of donors on the basis of high resolution (allele-level) HLA typing. Graft-versus-host disease and associated problems remain major challenges after allogeneic transplantation. Autologous stem cell transplantation may be beneficial for selected patients who have obtained complete remissions with conventional chemotherapy.