Low dose of indocyanine green emits near-infrared fluorescence, which can penetrate thin tissues like breast or skin. The operator can track the lymphatic pathway without skin incision in real time. By these characteristics, indocyanine green is currently used for sentinel lymph node biopsy in breast cancer surgery. Indocyanine green can also stain lymph nodes beyond the sentinel lymph nodes. This is why we can identify the lymphatic metastasis pathway of breast cancer.