We observed two patients with acute myeloid leukemia (AML) exhibiting trisomy 10 as the sole chromosome abnormality at the time of diagnosis. One patient was diagnosed with AML-MO, and the other with AML-M2. Both cases were CD7-antigen positive. However, we could not find any distinct clinico-hematologic characteristics of AML with trisomy 10 in these two patients. Trisomy 10 might be a rare recurring numerical chromosome abnormality and the incidence may be about 0.5% in de novo AML.