Reduced-intensity allogeneic transplantations for myelodysplastic syndrome (MDS) patients have been limited by significant graft-versus-host disease (GVHD), treatment-related mortality, and disease relapse. We treated 18 MDS patients ineligible for standard allogeneic transplantation with a preparative regimen of photopheresis day -7 and -6, pentostatin 4 mg/m(2) by continuous infusion day -5 and -4, and total body irradiation 600 cGy in 3 fractions day -3 and -2, followed by allogeneic stem cell infusion from 6/6 or 5/6 HLA-matched related donors or 6/6 HLA-matched unrelated donors. GVHD prophylaxis consisted of cyclosporin A and a short course of methotrexate. The median age was 54 years (range, 30-70 years). Diagnoses included refractory anemia (n = 2), refractory anemia with ringed sideroblasts (n = 2), refractory anemia with excess blasts (n = 10), refractory anemia with excess blasts in transformation (n = 3), and chronic myelomonocytic leukemia (n = 1). Sixteen of 18 patients developed full donor chimerism with no day +100 transplant-related mortality. Grade II to IV acute GVHD and extensive chronic GVHD developed in 19% and 18% of patients, respectively. Disease relapse occurred in 2 patients. At a median follow-up of 14 months (range, 1-35 months), the 1-year failure-free and overall survival were 64% and 65%, respectively. Our photopheresis and pentostatin-based reduced-intensity preparative regimen for allogeneic bone marrow transplantation in high-risk MDS patients achieves successful donor engraftment and disease remission with less transplant toxicity and grade II to IV acute GVHD.