We have investigated whether immunophenotyping measured by laser flow cytometry could be corresponding to FAB classification of acute leukemias, using multi-parametric analysis. Sixty-one patients with acute leukemias have been evaluated, including 23 patients with acute lymphocytic leukemias (ALL) and 38 patients with acute myelogenous leukemias. In principal component analysis, positive cell surface antigens could be classified into groups along to the cell lineage and differentiation. In discriminant analysis, the sensitivity by immunophenotypic method to FAB subtypes was 75%, whereas the specificity was over 90%. In cluster analysis, patients have been classified into 4 groups, which essentially corresponded to ALL, M1/M2, M3 and M4/M5. Based on those multi-parametric analysis, a new flow chart has been established, resulting that the sensitivity and the specificity was improved to over 90% and 95% respectively. These results suggest that the classification of acute leukemia using the flow chart could be useful tools for diagnosis of subtypes of acute leukemias.