The initial reports of sentinel lymph node mapping for breast cancer currently appearing in the surgical literature are demonstrating the practicality and accuracy of the technique to evaluate patients for axillary nodal disease. We reviewed our initial 100 patient experience with sentinel node mapping to evaluate our ability to employ this technique in breast cancer patients. We combined a peritumoral injection of a radioactive substance and blue dye. Each sentinel node was evaluated with frozen section analysis, hematoxylin and eosin staining, and, if still negative, five re-cuts were taken from deeper levels of the node and evaluated for immunohistochemical evidence of cytokeratin staining. Sentinel node(s) were identified in all but two patients with 51% demonstrating metastasis. We have demonstrated the ability to accurately perform sentinel node mapping in the evaluation of our breast cancer patients. This exciting advance should become a standard part of breast cancer surgery.