Azacitidine is approved in the EU for the treatment of adult patients who are not candidates for allogeneic stem cell transplantation, and who have intermediate-2 risk or high-risk myelodysplastic syndromes, according to the International Prognostic Scoring System. The approval includes the treatment of patients with acute myeloid leukemia (AML) with 20%-30% blasts and multilineage dysplasia, according to the World Health Organization (WHO) classification. This review focuses on the outcomes with azacitidine in this latter group of patients, previously classified as refractory anemia with excess of blasts in transformation, as defined by the French-American-British classification criteria. The main clinical evidence is based on the results of two large phase III clinical trials (Cancer and Leukemia Group B 9221, and AZA-001). The AZA-001 trial shows azacitidine significantly prolongs median overall survival in older patients with low marrow blasts (20%-30%) according to WHO-defined AML, and significantly improved several patient morbidity measures, compared with conventional care regimens. In addition, the review examines the results of azacitidine in combination with other treatments currently used in AML.