In acute myeloid leukemia (AML) FLT3 internal tandem duplication (ITD) and nucleophosmin 1 (NPM1) mutations provide prognostic information with clinical relevance through choice of treatment, but the effect of age and sex on these molecular markers has not been evaluated. The Swedish AML Registry contains data on FLT3-ITD and NPM1 mutations dating to 2007, and 1570 adult patients younger than 75 years, excluding acute promyelocytic leukemia, had molecular results reported. Females more often had FLT3ITD and/or NPM1mut (FLT3ITD: female, 29%; male, 22% [P = .0015]; NPM1mut: female, 36%; male, 27% [P = .0001]), and more males were double negative (female, 53%; male, 64%; P < .0001). Patients with FLT3ITD were younger than those without (59 vs 62 years; P = .023), in contrast to patients with NPM1mut (62 vs 60 years; P = .059). Interestingly, their prognostic effect had a strong dependence on age: FLT3ITD indicated poor survival in younger patients (