Lymphatic mapping with sentinel lymph node biopsy (SLNB) was introduced in the 1990s as a method to stage the nodal axilla in women with breast cancer. Very quickly the technique became the standard of care because pathologic staging was more accurate and sensitive and the surgical procedure resulted in low morbidity. SLNB has continued to evolve, and the applications in breast cancer have been expanded. A review of the published data was performed to update the lymphatic mapping technique and identify key issues and trends in the application of SLNB in women with breast cancer in 2015. The importance of axillary staging continues to effect the surgical treatment of patients with breast cancer. Originally described for patients with invasive cancer, the technique now plays an important role in staging women with ductal carcinoma in situ or recurrent breast cancer and patients with advanced breast cancer who are receiving neoadjuvant chemotherapy. Histologic examinations have incorporated multiple sectioning and immunostains. The morbidity has been low, and techniques for limiting lymphedema are being introduced. Lymphatic mapping will continue to play an important role in the treatment of women with breast cancer. The SLNB will evolve by eliminating the need for radioactivity in the operating room, and the technique will become more accurate and used in expanded indications by incorporating preoperative imaging and intraoperative guidance procedures.