A 38-year old man was transmitted to our hospital because of his pneumonia and disconsciousness. Laboratory data showed leukocytosis (32,500/microliter), mild anemia, and decreased platelet count (6.7 x 10(4)/microliter). The bone marrow aspiration revealed the presence of 40% blastoid cells and cytogenetic study showed abnormal karyotype, 45, X, -Y, t(8; 21) (q22; q22), indicating acute myeloid leukemia (AML, M2). Furthermore, on the microscopic observation, cell fragments resembling giant platelets were observed which were positive for myeloperoxidase, and several fragments connected with abnormal promyelocytes through thin cytoplasm. These results suggested these cell fragments may be produced from abnormal promyelocytes in this case.