Objective: To study the expression of Gadd45a and p53 protein in breast cancer and its correlation with clinical pathologic features in breast cancer. Methods: The expressions of Gadd45a and p53 proteins in 78 cases of breast cancer and mammary gland tissues were determined by the immunohistochemical staining. Results: The expression of Gadd45a in patients was lower than that in the control mammary gland tissue,while the expression of p53 in cancer samples was higher than that in the adjacent mammary gland tissue (P < 0.05). The positive rate of Gadd45a correlated differentiation level of cancer (Grade I,83.3%,Grade II,46.7%,Grade III,16.7%,P < 0.05),meanwhile,the positive rate of p53 in patients with lymph node metastasis was 76.6%,which was much higher than that in no metastasis patient (48.4%,P < 0.05). p53 correlated with Gadd45a negatively. Survival analyses showed significant differences between the positive class and negative class of these three proteins[MST(median survival time):Gadd45a:57.3m,46.3m;p53:47.7m,58.6m,5-year survival rate:Gadd45a:89.6%,60.0%;p53:70.6%,92.6%]. Survival analyses shown significant differences between the positive class and negative class of p53(+)Gadd45a(-)[MST:p53(+)Gadd45a(-):37.5m;58.3m,5-year survival rate:p53 (+)Gadd45a (-):50.0%,89.2%]. Conclusion: Gadd45a and p53 testing could predict the invasive behavior of breast cancer. The expression of Gadd45a correlates with a favorable prognosis,and the expression of p53 correlates with unfavorable prognosis,p53 (+)Gadd45a (-)predict poor prognosis. Gadd45a and p53 could be developed to be a new breast cancer therapeutic target.