A 32-year-old man was newly diagnosed with acute myelocytic leukemia, classified as acute myeloblastic leukemia with maturation (AML-M2) according to the French-American-British classification system. Conventional chromosome analysis before chemotherapy treatment revealed an abnormal karyotype: a possible segmental duplication of 11q23, plus a translocation between chromosomes 15 and 17 [t(15;17) (q22;q21.1)] in the majority of cells analyzed. Fluorescence in situ hybridization analysis using commercially available probes confirmed the cytogenetic findings. To our knowledge, this is the first report of a combination of t(15;17) and a segmental duplication of 11q23 in a patient with AML-M2.