Background: Biomarkers accepted for clinical use in breast cancer have low sensitivity and specificity. Thus, there is a need for new markers to assist in the diagnosis, prognosis and follow-up of breast cancer patients. This study aims to investigate the diagnostic, prognostic and follow-up role of serum Bcl-2, Bax and p53 proteins in breast cancer patients in comparison with those of serum CA 15-3 as the most commonly used breast cancer marker.Methods: We analyzed 50 breast cancer patients (before surgery, after one month of surgery and after six cycles of chemotherapy) and 50 normal healthy controls for serum Bcl-2, Bax, p53 and CA 15-3 levels.Results: Mean serum Bcl-2 and CA 15-3 levels significantly increased, whereas the mean serum p53 level significantly declined in breast cancer patients compared to normal healthy controls. Using the ROC curve analysis, serum p53 had the greatest area under the curve (85.6%). Serum Bcl-2 levels significantly decreased after six cycles of chemotherapy compared with its level one month after surgery. Preoperative serum levels of Bcl-2, Bax, p53 and CA 15-3 were non-significantly correlated with patient's disease-free survival.Conclusion: Serum p53 was superior to Bcl-2 and CA 15-3 in the diagnosis of breast cancer patients. Only Bcl-2 could be used for monitoring the effect of chemotherapy on breast cancer patients. None of the assayed biomarkers had a role in monitoring the effect of surgery on breast cancer patients. None of the assayed biomarkers had a prognostic role for breast cancer patients.