This retrospective study analyzed the impact of demographic and transplantation variables on outcomes of 1108 patients who have undergone allogeneic hematopoietic stem cell transplantation after reduced intensity conditioning (RIC HSCT) for hematological malignancies and were reported to the Société Française de Greffe de Moelle et de Thérapie Cellulaire registry between November 1994 and December 2004. Only 442 patients (40%) were in complete remission (CR) at time of transplantation. Peripheral blood stem cells were used in the majority of patients (n = 878; 79%), 255 patients received fludarabine and low-dose total body irradiation, while 465 patients (42%) fludarabine and busulfan with rabbit anti-thymocyte globulins (ATG). The impact of demographic and transplant variables was studied on overall (OS) and event-free survival (EFS) in univariate and multivariate analysis. With a median follow-up of 21 months, 3-year probability of OS and EFS was 42% and 30%, respectively, and treatment-related mortality was 15% at 2 years. The multivariate analysis showed a significant negative impact on OS and EFS of the absence of CR status before transplantation; conditioning regimen, including >10 mg/kg ATG; and minor ABO incompatibility. In conclusion, this study highlights the major impact on RIC HSCT outcome of disease status before transplantation, ATG dose and ABO incompatibility.