PURPOSE: This study aimed to evaluate the identification rate and surgery time of sentinel lymph node biopsy (SLNB) by a multimodal method (MMM) using a mixture of indocyanine green (ICG), radioisotope (RI), and blue dye (BD) compared with the RI alone. METHODS: In this phase II randomized study, 86 patients with clinically node-negative breast cancer were enrolled and received SLNB with either MMM or RI. We compared the identification rate, number of sentinel lymph nodes (SLNs), and detection time of SLNB and evaluated the safety. RESULTS: The mean age of the MMM group and RI group was 48.2 and 51.0 years (p = 0.12), respectively. There were no differences in histopathologic factors, including tumor size, node positivity, and hormone receptor positivity between groups. SLNs were identified in all patients of both groups (100 % in the MMM group and 100 % in the RI group). The average number of SLNs in the MMM group was more than that in the RI group (3.4 ± 1.37 vs. 2.3 ± 1.04, respectively; p < 0.001). The time to detect the first sentinel lymph node was similar in each group (6.5 ± 5.16 vs. 8.0 ± 4.35 min; p = 0.13). In the MMM group, percutaneous lymphatic drainage was visualized by fluorescent imaging in 90.7 % (39 of 43 patients). During and after the operation, there were no complications, including allergic reactions, skin staining, or necrosis. CONCLUSIONS: This study is the first randomized trial that compared MMM using ICG, RI, and BD and the conventional RI method for SLNB. MMM is a feasible and safe method for SLNB.