Background:The sentinel lymph node (SLN) is the first lymph node to receive lymphatic drainage from a primary breast tumor. If the SLN contains no metastatic tumor, then it is unlikely other lymph nodes will contain breast cancer metastasis. When the SLN does contains metastasis, an axillary lymph node dissection (ALND) is recommended to further stage the axilla and to maintain locoregional control. SLNs can be identified by using a dye, radioisotope, or combined techniques. Objective: To determine the rate of SLN identification using isosulfan blue dye in breast cancer patients at Charoenkrung Pracharak Hospital, Thailand, and factors that affect it. Methods: This prospective study of 106 consecutive cases breast cancer enrolled 105 women (1 bilateral breast cancer case) between October 2011 and October 2013 at Charoenkrung Pracharak Hospital. Clinical and pathological features were analyzed for the effectiveness of SLN identification using isosulfan blue dye. Results: The rate of SLN identification using isosulfan blue dye in breast cancer patients at Charoenkrung Pracharak Hospital was 92%. The method was safe and well tolerated in early-stage breast cancer patients. Conclusion:The effectiveness of sentinel node identification using isosulfan blue dye in breast cancer patients at Charoenkrung Pracharak Hospital is consistent with that shown in studies from other countries.