Cytoreduction before allogeneic stem cell transplantation (allo-SCT) for patients with myelodysplastic syndromes remains a debatable issue. After excluding patients who had received preconditioning induction chemotherapy, we analyzed 128 consecutive patients with myelodysplastic syndrome who received reducedintensity or nonmyeloablative conditioning (RIC/NMA) allo-SCT. Among them, 40 received azacitidine (AZA) before transplant (AZA group) and 88 were transplanted up front (best supportive care [BSC] group). At diagnosis, 55 patients had intermediate 2 or high-risk scores per the International Prognostic Scoring System and 33 had a high cytogenetic risk score. Progression to a more advanced disease before allo-SCT was recorded in 22 patients. Source of stem cells were blood (n ¼ 112) or marrow (n ¼ 16) from sibling (n ¼ 78) or HLA-matched unrelated (n ¼ 50) donors. With a median follow-up of 60 months, 3-year overall survival, relapse-free survival, cumulative incidence of relapse, and nonrelapse mortality were, respectively, 53% versus 53% (P ¼ .69), 37% versus 42% (P ¼ .78), 35% versus 36% (P ¼ .99), and 20% versus 23% (P ¼ .74), for the AZA group and BSC group, respectively. Multivariate analysis confirmed the absence of statistical differences in outcome between the AZA and BSC groups, after adjusting for potential confounders using the propensity score approach. The absence of cytoreduction before RIC/NMA allo-SCT did not seem to alter the outcome. However, our results emphasize the need to perform prospective protocols to delineate the role of debulking strategy and to identify subsets of patients who may benefit from this approach. ; Peer reviewed