The present study examined mitotic count, expression counts of Cyclin A2, Cyclin B1, Cyclin E, and PHH3, and labeling indices of Ki-67 and Survivin, to determine the best index for proliferation related to the differentiation of malignant phyllodes tumors in the histologically graded phyllodes tumors according to the WHO classification. The gene discussed is CCNA2; the disease is phyllodes tumor.