We performed a retrospective population-based cohort study of acute myeloid leukemia (AML) in Miyazaki Prefecture, Japan. Over 6 years, we diagnosed 221 patients (211 adults and 10 children) with AML, indicating an incidence of AML in Miyazaki Prefecture of 3.2 per 100,000 per year. In 193 adult patients with non-acute promyelocytic leukemia (APL), the proportion of patients with myelodysplasia, unfavorable risk karyotypes, antecedent hematologic diseases, prior chemotherapy for other malignancies, and small proportion of blasts in the marrow was higher in patients ≥65 years, and patients with poor performance status (PS) and higher WBC counts at diagnosis were more prevalent among patients ≥75 years. One-third of the adult non-APL patients met the inclusion criteria usually applied in clinical trials: de novo AML, age ≤64 years with PS 0-2 and no key organ dysfunction. The 5-year overall survival (OS) rate of adult non-APL patients was 21.1 % (patients ≤64 years, 33.8 %; 65-74 years, 21.6 %; ≥75 years, 0 %). Multivariate analysis revealed that French-American-British subtypes M0, M6, and M7, poor PS (3, 4), unfavorable risk karyotypes, and higher WBC counts at diagnosis were independent adverse prognostic factors associated with OS. This analysis provides real world data.