Objective To investigate the expression of ER,PR,HER-2,PCNA and P53 in breast cancer patients in Shanghai and the relevant clinical significance.Methods Expressions of ER,PR,HER-2,PCNA and P53 in the breast cancer tissues of 544 patients in Shanghai were detected by immunohistochemistry methods.Statistical analysis was applied to analyze the relationship of these immunohistochemical indices with the clinicopathological features of breast cancer.Results The positive rates of ER,PR,HER-2,PCNA and P53 in the breast cancer tissues of 544 patients were 62.2%,57.2%,15.1%,82.6% and 58.5%,respectively.The expressions of ER,PCNA and P53 were correlated with the tumor size(P