Sentinel lymph node biopsy is an accepted standard of care for staging the axilla in patients with early-stage breast cancer. Little attention has been placed to the presence of intramammary sentinel lymph nodes (intraMSLNs) on preoperative lymphoscintigraphy.Between December 2001 and September 2006, in 9632 breast cancer patients with clinically uninvolved axillary nodes, lymphoscintigraphy was performed at the European Institute of Oncology (EIO). An axillary SLN (axSLN) was identified in 99.4% of cases. An intraMSLN was identified in association with the axillary sentinel lymph node in 22 patients (0.2%). In 15 cases both the axSLN and the intraMSLN were excised.The intraMSLN was positive in six patients (micrometastatic in three cases). The axSLNs were negative in all 15 cases. Two patients with positive intraMSLNs and one patient with a negative intraMSLN underwent axillary dissection; all three cases had negative axillary nodes. At a median follow-up of 24 months, no locoregional or systemic recurrences were observed.Positive intraMSLNs can improve disease staging but do not necessarily portend axillary lymph node metastasis. When intraMSLNs and axSLNs are present, we advocate biopsy of both sites and that management of the axilla should rely on axSLN status. In cases with intraMSLNs as the only draining site on lymphoscintigraphy, decisions on axillary management should be made on individualized basis.