The incidence of acute myelogenous leukemia (AML) in patients over 80 years old is >20 times greater than that observed in younger patients. Previously, no standard treatment protocol for elderly patients with AML existed, however the development of hypomethylating agents, including decitabine, has brought about promising results in AML. In the present study, we report on the usage of a lower than routine dosage of decitabine in patients over 80 years old with AML. Since January 2010, 5 patients diagnosed with AML over the age of 80 years old received treatment with decitabine in our hospital. Decitabine was administered at a dose of 10-15 mg/m2 and repeated every other day for a total of 5 days. This cycle was repeated for ∼6 weeks. The 5 patients received a total of 19 cycles of treatment with decitabine. No patient achieved complete or partial remission. An antileukemic effect was observed in 25% of courses (3/12). An increase in platelet count of >20×109/l was observed in 26.3% (5/19) of cycles compared with previous treatment. An increase in hemoglobin concentration of >20 g/l was observed in 36.8% (7/19) of cycles in comparison to previous treatment, four of which achieved normal hemoglobin levels. One patient became red blood cell transfusion-independent. The median survival time was 19.8±4.8 months. Survival time from decitabine administration to mortality was 13.2±5.1 months. The main side-effect was bone marrow suppression with grade III-IV thrombocytopenia, grade III-IV leukocytopenia, grade III-IV neutropenia and anemia accounting for 94.7% (18/19), 47.4% (9/19), 89.5% (17/19) and 21.1% (4/19), respectively. Severe infection or bleeding was not observed and no patient stopped treatment due to adverse effects. In conclusion, extremely low-dose decitabine may be used safely in elderly patients and achieved longer survival times than reported previously in AML patients aged 80 and above. It is suggested that complete remission may not be the primary objective, while improvement of quality of life may be a better choice in AML patients over 80 years old. The cases observed in our study were limited, so more cases are required for further study.