As past studies of adolescent and young adults (AYA) with acute myeloid leukemia (AML) reported conflicting results, we conducted a retrospective analysis using data from three Japanese pediatric AML studies. Among the 782 patients with de novo AML, 44 were classified as AYA (age ≥15 years at diagnosis), 164 as infants (0-1 year), 413 as younger children (2-11 years), and 161 as older children (12-14 years). While the 5-year event-free survival rate of AYA was not different among the groups, the five-year survival rate (54.7 %) was significantly lower than that of the other three groups (P = 0.019): 68.7 % for infants, 73.2 % for younger children, and 75.5 % for older children. No difference in the 5-year cumulative incidence of relapse was observed, but treatment-related death (TRD) of AYA was significantly higher (29.4 %) than that in infants (14.8 %), younger children (10.2 %), and older children (13.8 %). Multivariate analysis showed age ≥15 years old at diagnosis was associated with both poor survival rate and high TRD. Adolescents with AML had inferior survival due to a higher incidence of TRD, especially after failure of initial frontline treatment.