[en] Aim: Tumor markers are potentially powerful means for obtaining information about cancers whilst causing minimal morbidity, inconvenience and cost. CA 15-3 and CEA are considered useful tumor markers in monitoring breast cancer patients. The aim of this study was to evaluate which of these two markers are in better correlate with the disease in patients surgically treated for breast cancer. Material and Methods: We retrospectively reviewed values of CA15-3 and CEA in 342 patients (median age 52.18 years, range 27-78 years) with surgically treated and pathologically proven breast cancer. CA15-3 and CEA was measured by radioimmunoassay. CA15-3 levels above 30 U/ml and CEA levels above 5 ng/ml were considered as positive values. Results: Out of 342 patients, 86 had elevated CA15-3 levels (sensitivity: 25.1%) and 68 of 342 patients had positive CEA levels (sensitivity 19.9%). Two hundred thirty seven (237) of the patients suffering from breast cancer (69.3%) did not have metastatic disease. In this group CA15-3 sensitivity was 94.5%, while CEA sensitivity was 87.3%. One hundred and five (105) patients (30.7%) had metastatic disease. In this group, CA15-3 sensitivity was 69.5% and CEA sensitivity was 36.2% (P < 0.05). With regard to the correlation of the two tumor markers with clinical course patients had significantly higher levels of CA15-3 than of CEA in metastatic breast cancer. Conclusion: This result suggests CA15-3 to be the more sensitive and more specific of the two tumor markers for metastatic breast cancer detection and monitoring