Owing to recent technical developments in automated hematology analyzers, identification of 5-part differential counts in white blood cells and also of abnormal leukocytes has become possible. Blood specimens from 200 patients with leukemic hematologic conditions were processed through a Coulter STKS which gives a favorable white cell differential count utilizing the following parameters: volumetric impedance (V), electric conductivity/cell volume (C), and a monochromatic laser beam which provides collectively white cell scatterplot (S). To analyze the presented figures of a pathologic scatterplot (SP) on the visual display unit, the standard scale derived from 220 normal SP patterns which was composed of four kinds of cell SP scales (neutrophil: N, monocyte: Mo, eosinophil: Eo, lymphocyte: Ly) was applied. Leukemic SP figures were variable depending upon both the type of FAB classification and their therapeutic processes. SP forms of M0-blasts were semi-round and located in the central area surrounded by N-, Mo-, and Ly-SP scale. Blast SP of M1 and M2 was shown as a developing process to the SP field containing immature myeloid cells extending from the central area. It was reasonable that immature neutrophilic SP expression was obtained in M3 and Ph1 positive CML. However, the SP of M3v and Ph1 negative CML showed myelomonocytic features as CMMoL does. Typical myelomonocytic SP patterns were obtained in M4 patients. SP figures of MDS were characterized by deformability, dislocation and another abnormality, and these changes, especially in lymphocytes are very useful for diagnosis of MDS. Therefore, the FAB subtype of AML including MDS and CML could be distinguished from each other on the basis of SP pattern. In lymphoproliferative disorders, limited conductivity in ALL-SP was characteristic, while irregular and deformed SP was peculiar in leukemic malignant lymphoma. It would be a valuable process to analyze the SP pattern obtained from an automated hematology analyzer for identification of leukemic diseases.