Axillary clearance in breast cancer has been proven to be unnecessary in more than 50% of cases. Sentinel node biopsy (SNB) is a new technique that can be used to avoid unnecessary axillary clearance in breast cancer surgery. Our integrated team, consisting of surgeons, pathologists and nuclear medicine physicians, studied 48 cases of T1 breast cancer with lymphoscintigraphy-guided SNB. Before starting this study, the team performed 20 SNBs as a learning procedure. 500 microCi of 99mTc-nanocoll in 0.2 mL were injected around the lesion, under US or x-ray guidance if necessary. Static images in anterior, lateral and lateral oblique view collected at the end of a 20 min dynamic study were used to mark the SN on the skin. During surgery a gamma probe was used to guide SN resection, and node invasion was assessed with cytokeratin immunohistochemistry. In 14 patients tracer uptake was observed in a single node, in 30 patients in 2-4 nodes, whereas in four patients the nodes were scintigraphically missed. Surgical resection was possible in 42 nodes out of 54. All but two patients with negative immunohistochemistry for cancer cell clusters showed metastasis-free axillary nodes. All patients with positive SNBs (13) showed involved axilla. In four patients the lymphatic drainage was towards the intramammary chain; one node was juxtaclavicular and one node was intramammary in the upper outer quadrant. The overall sensitivity of the method was about 80%, the specificity about 90% with a diagnostic accuracy about 80%. SNB is a promising method for surgical decision-making regarding axillary clearance in breast cancer. Adequate training of an interdisciplinary team is needed in order to successfully perform SNB and assess SN invasion. Its unusual anatomic location can be encountered and technical care is necessary to correctly identify and remove them.