Background and aim of the work: Serum tumor markers; carcinoembryonic antigen (CEA) and cancer antigen 15-3 (CA15-3) are widely used in clinical practice for detecting recurrences or monitoring treatment efficacy for metastatic breast cancer patients. We aimed to explore the relationship between serum levels of CEA, CA 15-3 before neoadjuvant treatment and clinicopathological parameters in breast cancer patients, as well as the predictive value of these two serum biomarkers in relation to response to neoadjuvant chemotherapy. Methods: This prospective study was conducted at Helwan University Hospitals from October 2022 to September 2023. It included 50 breast cancer patients who received neoadjuvant chemotherapy. Results: Higher T status, higher LN status and higher stage were significantly associated with higher CEA, CA 15-3 levels. While there was no statistically significant correlation between the level of CEA, CA 15-3 and molecular type or histopathological type. There was no statistical difference in serum levels of CEA and CA 15-3 between patients with partial and patients with complete response. Conclusion: Pretreatment serum levels of CEA and CA15-3 were elevated in the majority of breast cancer patients. Higher T status, higher LN status and higher stage were significantly associated with higher CEA & CA 15-3 levels which can be related to prognosis. CEA and CA 15-3 had no significant association with molecular subtypes or response to neoadjuvant chemotherapy.