Background: Breast cancer is a disease with heterogenous nature. Its behavior is unpredictable. There has recently been much interest in the biological parameters for breast cancer as they may provide useful information on the clinical outcome. Among these parameters c-erbB2 and p53 are of special importance. The present study was designed to determine the protein levels of c-erbB2 and p53 in breast tumor tissues by ELISA technique correlating the levels with clinicopathological behavior of tumors. Materials and Methods: C-erbB2 and p53 protein levels were determined by ELISA technique in 40 malignant breast tissues, 20 benign breast disease tissues and 15 healthy breast tissues. These tissues were obtained during operations of mastectomy and lumpectomy. Results: C-erbB2 and p53 protein levels were significantly increased in malignant breast tissues compared to either benign or healthy tissues. The levels were correlated with advanced stage, number of lymph nodes involved, tumor burden, ductal carcinoma and bad prognosis. Significant positive correlation (r=0.72 & P <0.001) existed between p53 and c-erbB2 protein levels. Conclusion: Based on these finding c-erbB2 and p53 are important predictors of breast cancer biological behavior. Therapeutic modalities directed against these genes in patients over-expressing them could be of great therapeutic results.