Abstract: Objective　To reportthe cell biology characteristics of the abnormal expression of cCD79a in 7 cases of acute myeloid leukemia（AML）-M2 with t（8；21）（q22；q22） selectedfrom 190 AML children since 2005.   Methods　The characteristics of cell morphology，immunology，cytogenetics，molecular biology（MICM） and clinical manifestations in 7 cases of AML-M2 with t（8；21）（q22；q22） expressing cCD79a abnormally were analyzed. The control group including 20 cases of AML-M2 with t（8；21） was detected during the same period. Results　The 83 cases of AML-M2 t（8；21）（q22；q22） accountedfor 43.7% of 190 continuous childhood AML patients，and the percentage of the cCD79a expression in the 83 cases of AML-M2 t（8；21） was 8.4%（7 cases）. In the cases of AML-M2 with t（8；21）（q22；q22） expressing cCD79a abnormally，the bone marrow cell morphology showed the acute myelogenous leukemia M2. The initial cells all increased evidently in the classification. The immunophenotypes were all the expressions of myeloid markers with B-lymphoid. CD34 had high positive expression. There were changes of the chromosome with t（8；21）（q22；q22），also with the complexly translocation or depletion. The detections of the confluentgene AML1/ETO were positive. Ithad achieved good response to combined chemotherapy targeted to both myeloid and lymphoid leukemia. Conclusions　t（8；21） M2 is the mostfrequenttype of childhood AML. Itmay be related with abnormal expression gene of B lymphocyte phenotype. Key words：cCD79a；Acute myeloid leukemia；Immunophenotype；t（8；21） translocation

Key words: cCD79a, Acute myeloid leukemia, Immunophenotype, t（8, 21） translocation