ObjectiveTo explore the expression of Ki-67 antigen in the breast cancer tissues and to evaluate the relationship of the expression to biology behavior as well as prognosis of breast cancer. MethodLiteratures about relation between Ki-67 and breast cancer were reviewed. ResultsThe expression of Ki-67 in the breast cancer tissue was obviously higher than that in the adjacent to cancer tissue or normal breast tissue. The Ki-67 positive expression rate was positively correlated with pathology classification and clinical stage of breast cancer, the correlation was not consistent about the expression of Ki-67 and axillary lymph node metastasis of breast cancer. ConclusionsKi-67 is a cell proliferation nuclear antigen related to cell cycle, and its expression changes along with the change of cell cycle, it has been employed as a reliable marker of cell proliferation. The expression of Ki-67 has an important significance in early diagnosis and guiding of neoadjuvant chemotherapy as well as prognosis of breast cancer.