Abstract: Objective To investigate the expression and clinical significance of Ki-67 and p53 in breast invasive ductal carcinoma(IDC).Methods Immunohisto chemical SP method was applied to detect the expression of Ki-67 and p53 protein in 42 cases with IDC and 18 cases with benign breast lesions, statistical analysis was performed to correlate the expression of Ki-67 and p53 with their clinical parameters.Results The positive expression percentage of Ki-67 and p53 was significantly higher in IDC cases than that in benign lesions cases(78.6% VS 0, 38.1 VS 5.6%).There was significant association between Ki-67, p53 expression and TNM staging, Ki-67 and p53 increasing correlated with higher TNM staging.There was another significant association between Ki-67 expression and tumor size.Conclusion The findings suggest that the positive expression of Ki-67 and p53in IDC make a closed correlation with TNM staging, Co-determining the expression of Ki-67 and p53in IDC case may play an important role in prediction of the IDC prognosis.