After a peak during the first 2 years of life, the incidence of acute myelogenous leukemia (AML) is low (five per million 5- to 9-year-olds per year in the United States) until after 9 years of age, when it slowly increases during adolescence and adulthood (to nine per million per year among 15- to 19-year-olds in the United States). Biological features including the prevalence of some genetic abnormalities appear to differ between pediatric and young adult AML. Treatment results in AML have improved during the last 30 years for all age groups; however, survival decreases with advancing age even when genetic risk factors are considered. In contrast to data about children and older adults, data on biological features and outcome are scarce in the adolescent and young adult (AYA) age group. This is partly due to the low number of patients of this age group participating in clinical trials. Differences in outcome for AYAs participating in pediatric trials compared to adult trials seem to be significant when different protocols are used, but minor with similar or identical protocols. As the needs of AYAs are different from those of young children and those of older adults, it is recommended to treat these patients in special units whenever possible.