Objective To investigate multiparametric immunophenotypic features in patients with acute myelocytic leukemia(AML)-M_2 bearing AML-1/ETO gene rearrangements and its predicting value.Methods A multiparametric flow cytometry was used in the study of phenotypic characterization of the subtype of AML.Immunophenotype of 30 patients with AML(M_2/ETO~+)was analyzed by fluorescence in situ hybridization(FISH).The results were compared with 36 patients of AML-M_2 with AML-1/ETO~- (M_2/ETO~-)and 34 acute promyelocytic leukemia(APL)patients.Results There were a population. 15.89%-68.53% the blast cell and a population of more differentiated and heterogeneous myeloid cells in the marrow of 30 patients with M_2/ETO~+.The blast cells had a myeloid phenotype(CD_(33),CD_(13)and MPO) and showed a characteristic pattern of antigen expression.The fluorescent intensity of CD_(33)in patients with M_2/ETO~+ was less than in patients with M_2/ETO~-and APL [ mean fluorescent intensity(MFI):98?75 v. 244?184 and 845?523,both P