Reduced-intensity conditioning has extended the use of allogeneic hematopoietic stem cell transplantation (HSCT) to patients otherwise not eligible for this treatment due to older age or frailty. One hundred twelve acute myelogenous leukemia/myelodysplastic syndromes patients received fludarabine and melphalan (FM) conditioning with allogeneic HSCT. Most patients (73%) were not in remission. Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus and mini-methotrexate. Median age was 55 years (range, 22-74). Donors were related (53%) and unrelated (47%). Median follow-up of surviving patients (n = 43) was 29.4 months (range, 13.1-87.7). The complete remission (CR) rate was 82%. Estimates of 2-year survival were 66%, 40%, and 23% for patients in CR, with active disease without and with circulating blasts at HSCT, respectively. In multivariate analysis, survival was negatively influenced by active disease at HSCT and development of grade II-IV acute GVHD. Presence of circulating blasts at HSCT negatively influenced freedom from disease progression. Incidence of nonrelapse mortality (NRM) was significantly higher for patients with active disease, but was not influenced by patient age. Patients in CR had a day-100 and 2-year NRM of 0% and 20%, respectively. Use of unrelated donors increased the risk of NRM only among patients with active disease. FM and HSCT elicited long-term disease control in a significant fraction of this high-risk cohort. © 2007 American Society for Blood and Marrow Transplantation.