Currently, more than half of patients with acute myeloid leukemia (AML) are elderly. The prognosis is usually poor in these patients. Even among young people, there are still some cases with refractory or relapsed disease. Prognostic factors are categorized into leukemic, stage, and host factors. In elderly patients, the importance of host factors is increased relative to other factors. Cognitive and physical conditions should also be evaluated. Fitness for chemotherapy followed by hematopoietic cell transplantation is then determined. High-dose cytarabine or a purine nucleoside analogue combined chemotherapy is an option for treating relapsed or refractory cases. Gemtuzumab ozogamicin (GO) is not effective for single use. Results of clinical trials for GO combined chemotherapy were split. Doses and schedules still need to be discussed. Low dose chemotherapy has no survival benefit for elderly people. DNA hypomethylating agents have limited effects but do not achieve a cure. Novel drugs are under development. FLT3 inhibitors and/or IDH inhibitors are expected to exert beneficial effects. No therapy superior to conventional chemotherapy has yet been developed.