BACKGROUND Breast cancer is the most common malignant cancer in women worldwide. The tumor markers Cancer Antigen 15-3 (CA15-3) and Carcinoembryonic Antigen (CEA) are frequently used for screening and monitoring breast cancer. MATERIAL AND METHODS We conducted a meta-analysis of 13 published case-control studies to assess the associations between serum levels of CA15-3 and CEA with breast cancer susceptibility, including 1179 cases and 493 controls. The analyses were performed on malignant tumor and benign tumor, as well as in different subgroups with respect to the patient ethnicities and clinical tumor stages. RESULTS This systematic review and meta-analysis of association studies shows that serum levels of CA15-3 and CEA are potential biomarkers for breast cancer monitoring. When stratified by clinical stage, we noticed that although malignant tumors in all stages show elevated levels of CA15-3, it is greatly associated with the tumor stage, as it increases as breast tumor stage worsens. CONCLUSIONS This study clarifies the inconsistent conclusions from multiple studies, and provides a precise estimation for clinical utility of 2 important biomarkers, CA15-3 and CEA, in breast cancer monitoring. Thus, our study will shed lights on the prognosis of breast cancer patients.