Purpose The tet oncogene family member 2 (TET2) gene was recently identified to be mutated in myeloid disorders including acute myeloid leukemia (AML). To date, there is increasing evidence for a functional role of TET2 mutations (TET2mut) in AML. Thus, we explored the frequency, gene-expression pattern, and clinical impact of TET2mut in a large cohort of patients with AML in the context of other AML-associated aberrations. Patients and Methods Samples from 783 younger adult patients with AML were analyzed for the presence of TET2mut (coding exons 3 to 11), and results were correlated with data from molecular genetic analyses, gene-expression profiling, and clinical outcome. Results In total, 66 TET2mut were found in 60 patients (60 of 783 patients; 7.6%), including missense (n = 37), frameshift (n = 16), and nonsense (n = 13) mutations, which, with one exception, were all heterozygous. TET2mut were not correlated with distinct clinical features or genetic alterations, except for isocitrate dehydrogenase mutations (IDHmut) that were almost mutually exclusive with TET2mut (P < .001). TET2mut were characterized by only a weak gene-expression pattern, which, nevertheless, reflected TET2mut-associated biology. TET2mut did not impact the response to induction therapy and clinical outcome; the combination of patients who exhibited TET2mut and/or IDHmut revealed shorter overall survival (P = .03), although this association was not independent from known risk factors. Conclusion TET2mut were identified in 7.6% of younger adult patients with AML and did not impact the response to therapy and survival. Mutations were mutually exclusive with IDHmut, which supported recent data on a common mechanism of action that might obscure the impact of TET2mut if compared against all other patients with AML.