Christopher Arthur,1 Jaroslav Cermak,2 Jacques Delaunay,3 Jirí Mayer,4 Grzegorz Mazur,5 Xavier Thomas,6 Agnieszka Wierzbowska,7 Mark M Jones,8 Erhan Berrak,8 Hagop Kantarjian9 1Department of Haematology, Royal North Shore Hospital, Sydney, NSW, Australia; 2Institute of Hematology and Blood Transfusion, Prague, Czech Republic; 3Department of Clinical Hematology, University of Nantes, Nantes, France; 4Department of Internal Medicine, Masaryk University Hospital Brno, Central European Institute of Technology, Brno, Czech Republic; 5Department of Hematology, Wroclaw Medical University, Wroclaw, Poland; 6Department of Hematology, Edouard Herriot Hospital, Lyon, France; 7Copernicus Memorial Hospital, Lodz, Poland; 8Oncology Product Creation Unit, Eisai Inc., Woodcliff Lake, NJ, USA; 9Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, USA Background: In a Phase III trial, 485 patients (≥65 years) with newly diagnosed acute myeloid leukemia received decitabine 20 mg/m2 intravenously for 5 days every 4 weeks or a treatment choice (supportive care or cytarabine 20 mg/m2 subcutaneously for 10 days every 4 weeks). Materials and methods: We summarized overall and progression-free survival by baseline white blood cell count using two analyses: 5×109/L; ≤10 or .10×109/L. Results: There were 446 deaths (treatment choice, n=227; decitabine, n=219). Median overall survival was 5.0 (treatment choice) versus 7.7 months (decitabine; nominal P=0.037). Overall survival differences between white blood cell groups were not significant; hazard ratios (HRs) favored decitabine. Significant progression-free survival differences favored decitabine for groups 1–5×109/L (P=0.005, HR =0.67), greater than 5×109/L (P=0.027, HR =0.71), and up to 10×109/L (P=0.003, HR =0.72). Conclusion: There was a trend toward improved outcome with decitabine, regardless of baseline white blood cell count. Keywords: decitabine, acute myeloid leukemia, prognosis, leukemia, adult