Mutation in ten-eleven-translocation oncogene family member 2 (TET2) has been extensively investigated in the context of several hematologic malignancies and occurs in 7%-23% of patients with acute myeloid leukemia (AML). 1-4 TET2 acts to demethylate DNA, and TET2 mutations are leukemogenic in animal models. 5-8 Any prognostic role played by TET2 mutation in a patient with normal karyotype (NK)-AML remains a subject of debate. 1, 2, 9-11 Although the prevalence of homozygous TET2 mutation is 14.8% in patients with TET2-mutated myelodysplastic syndrome, and 9.3% in patients with TET2-mutated AML, the prognostic role played by this genotype in the context of treatment outcomes has not been investigated in depth. 9, 12 In this study, we evaluated the prevalence of TET2 mutations in patients with NK-AML and tried to clarify the prognostic role played by TET2 mutation in patients with NK-AML, especially in those patients with homozygous mutation.