OBJECTIVE The primary lymphatic pathway of patients with breast cancer is toward the axilla, but lymph drainage is also possible towards the internal mammary chain and the supraclavicular fossa. In the current article, the development of breast cancer recurrences at these two sites after sentinel lymph node biopsy is reviewed. METHODS Since 1997, 803 patients underwent sentinel lymph node biopsy with intratumoral injection of 99mTc-nanocolloid and patent blue dye in The Netherlands Cancer Institute. All sentinel nodes as visualized on the lymphoscintigraphy images were pursued. The patients were followed prospectively for a median period of 34 months. Patients with a lymph node recurrence outside the axilla were identified and their lymphatic mapping procedures were reviewed. RESULTS Four of the 803 patients (0.5%) developed regional lymph node recurrences outside the axilla. One recurrence was located in the internal mammary chain, the other three in the supraclavicular bed. One or two of these patients also had an axillary recurrence. The sentinel node procedure had failed in two of the four patients. CONCLUSIONS The incidence of nodal recurrences outside the axilla is low. Although all extra-axillary sentinel nodes were pursued, some of these recurrences concern missed sentinel nodes that harbor metastasis. Identification of all sentinel nodes and subsequent treatment of the involved basins may reduce the risk of breast cancer recurrences in these unusual locations.