Sentinel lymph node (SLN) mapping in breast cancer patients could spare some of them axillary lymphadenectomy. The present study was designed to assess the efficacy of SLN biopsy by using a combination of two techniques: the dye and the radioactive, with subcutaneus periareolar tracer injection. 80 women, aged 33-79 year, with primary, invasive breast cancer, less than 5 cm, and clinically negative loco-regional lymph nodes were entered into the study. Identification rate of SLN was 88,8 %. Efficacy of SLN detection by the method used in the study was calculated on the basis of pathological reports of dissected lymph nodes. Sensitivity was 89,3 %, negative predictive value - 93,5 %, and false negative rate 10,7 %. In conclusion, the mapping of breast lymphatic system by using two techniques: the dye and the radioactive, with subcutaneus periareolar tracer injection, is an effective method of SLN detection in breast cancer patients. Statistical analysis demonstrated that out of clinical and pathological features considered, only surgical excisional biopsy may negatively affect the SLN identification rate.