Prognostic factors in 42 patients aged 11 to 62 (median 46) years, with myelodysplastic syndrome (MDS) or after leukemic transformation, who underwent allogeneic marrow transplantation between 1984 and 1999 were analyzed. Thirty-six had advanced disease morphology; 19 had leukemic transformation. Twenty-nine received a preparative regimen of BuCy2 and 13 busulfan 14 mg/kg, etoposide 50 mg/kg and cyclophosphamide 120 mg/kg. Severe hepatic veno-occlusive disease (VOD) occurred in three patients all of whom received anti-leukemic chemotherapy prior to transplantation. Fifteen patients (36%) died from early transplant-related complications; nine patients relapsed. The estimated 4 year disease-free survival (DFS) was 35% (95% CI 26-44%). Older age was the most significant adverse prognostic factor. Patients with leukemic transformation who underwent early transplantation had significantly better DFS than those treated first with chemotherapy (P = 0.002). Delayed toxicity was rare in these patients; no late relapses occurred. Bone Marrow Transplantation (2000) 25, 1219-1222.