Introduction: Azacitidine is a therapeutic alternative to low-dose cytarabine in patients with acute myeloid leukemia (AML) who are unfit for intensive chemotherapy. Patients and Methods: We retrospectively analyzed all AML patients treated with azacitidine at the University Hospital Zurich and the Kantonsspital Munsterlingen between January 2005 and December 2011. The primary end point was overall survival (OS). Results: Thirty-eight patients were included in the analysis. Twenty-one (55%) patients had newly diagnosed AML, 14 (37%) had relapsed AML, and 3 (8%) underwent bridging therapy before allogeneic stem-cell transplantation. Age at diagnosis was 72 years in the newly diagnosed cohort and 58 years in the relapsed cohort, 19 (50%) patients were female, 20 (53%) patients were transfusion dependent, and bone marrow blast count was 43% (interquartile range, 26-80). Most patients (58%) had poor or very poor risk AML. Patients received a median (range) of 7 (3-13) therapy cycles. The median (range) OS in the newly diagnosed and previously treated patient groups were 308 (175-580) days and 346 (293-628) days, respectively (P = .94). Median OS in the 3 patients treated before allogeneic stemcell transplantation has not been reached. Sixty-day mortality was 7.9%, with no difference between the 2 groups. Ongoing or increasing transfusion dependency was associated with adverse outcome (hazard ratio, 3.09; 95% confidence interval, 1.29-7.37, P = .011). Conclusion: Treatment with azacitidine led to a median OS of 10 months in both a previously untreated and a previously treated frail AML patient cohort. A positive effect in transfusion dependency was observed in 29% of these patients and was associated with better survival. AbstractIntroduction: Azacitidine is a therapeutic alternative to low-dose cytarabine in patients with