The existance of the metastatic axillary lymph node is the most important prognostic factor that plays role in the decision of the risk of invasion of the disease and in the decision of the adjuvant therapy. The aim of our study is to detect the sentinel lymph node (SLN) in early stage breast cancer cases by injecting radioactive colloid followed by the usage of the gamma-probe and to determine the relations between the pathological results of the ones of the SLN and the other axillary nodes. This study was performed on 54 cases of early stage breast cancer prospectively. Tc-99 m renium sulfur colloid under lymphoscintigraphy (0.5 milicurie) was injected to the quadrant of the site of the tumor subdermally and scintigraphic spots were taken afterwards. Following the detection of the SLN by the help of the gamma-probe, standard axillary dissection (Level 1-2) was applied to the patient. The results were observed in concepts of overall accuracy, false-negative rate, identification rate. Among the 54 cases that were included in this study 42 (77.8%) cases were Stage I and 12 (22.2%) cases were Stage II. The tumor was localized in the lateral quadrants in 34 (62%), and in the medial quadrants in 15 (27%) of the cases. Axillary drainage was detected in 52 cases (96%) and in 47 (87%) of these cases drainage was detected to be only to the axilla. In 2 (3.7%) cases drainage was detected to be only to the mammaria interna. The mean number of SLN detected in our study was 2.27. In 42% of our cases only a single node was detected. The detectability of the SLN by the gamma-probe is 98.15%. The false negative ratio is 5.3%. The SLN gives the same results with axillary dissection. There should be a small false negative ratio in order to rely on SLN biopsy.