Lymphatic mapping and sentinel lymph node mapping have changed the standard of surgical care for patients with melanoma and have the potential to do the same for women with breast cancer. The technique will result in more accurate disease staging and in less morbidity. Preoperative lymphoscintigraphy and the intraoperative mapping technique are being standardized across the country. With the lymphatic mapping technique, approximately 10% of the so-called histologic negative population will be more accurately staged. National trials are ongoing to determine the clinical significance of the missed micrometastatic