The use of reduced intensity conditioning (RIC) regimens for allogeneic stem cell transplantation (allo-SCT) can result in a significant decrease in early procedure-related toxicity in patients not eligible for standard myeloablative regimens. However, acute graft-versus-host disease (aGVHD) remains a matter of concern after RIC allo-SCT, and its incidence might be expected to be higher in elderly and high-risk patients. This report investigated mycophenolate mofetil (MMF) and cyclosporin A (CsA) combination (n=14) in comparison to CsA alone (n=20) for GVHD prophylaxis in cancer patients aged over 50 years (27 haematological malignancies and seven solid tumours) receiving an HLA-identical sibling antithymocyte-globulin (ATG)-based RIC allo-SCT. Baseline demographic characteristics and risk factors for aGVHD were comparable between both groups. Although MMF administration was not associated with any significant toxicity, the cumulative incidence of any form of GVHD was comparable between both groups (cumulative incidence of grade II-IV aGVHD, 50% (95% CI, 28-72%) for CsA alone, as compared to 64% (95% CI, 39-89%) to CsA and MMF, P=NS), suggesting that adjunction of MMF to CsA is feasible, but does not translate towards a significant reduction of aGVHD, at least in the context ATG-based RIC allo-SCT.