Abstract Objective: This self-controlled study aimed to investigate the feasibility of substituting indocyanine green (ICG) for radioisotope (RI) for combined imaging of axillary sentinel lymph node (SLN) in breast cancer. Study Design: Primary breast cancer, clinically axillary node-negative patients (n = 182) were prospectively enrolled from March 2015 to November 2020. ICG, methylene blue (MB), and RI were used to perform axillary SLNB. The main observation indices was the positivity of ICG + MB vs. RI + MB in axillary SLNB; the secondary observation indices were the axillary SLN detection rate, mean number of axillary SLN detected, mean number of metastatic axillary SLN detected and safety.Result: All 182 patients had axillary SLNs; a total of 925 axillary SLNs were detected. Pathological examination confirmed metastatic axillary SLN in 42 patients (total of 79 metastatic SLNs). Positivity, detection rate of SLNs, detection rate of metastatic SLNs, and the number of metastatic SLNs detected were comparable with RI+MB and ICG+MB (P>0.05). The mean number of axillary SLN detected was significantly higher with ICG+MB than with RI+MB (4.99±2.42 vs. 4.02±2.33, P<0.001). No tracer-related adverse events occurred.Conclusion: ICG appears to be a safe and effective axillary SLN tracer, and a feasible alternative to RI in combined imaging for axillary SLN of breast cancer. Citation Format: Yuting Jin, Long Yuan, Jun Jiang, Xiaowei Qi. A prospective self-controlled study of indocyanine green instead of radioisotope for axillary sentinel lymph nodes in breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-01-13.