Objective To study the influence of excisional biopsy on detection rate of sentinel lymph node biopsy through methylene blue in breast cancer.Methods A review of 76 patients with clinical stage T1-2N0M0 breast cancer who had a successful sentinel lymph node biopsy at the Affiliated Nanhai Hospital of Southern Medical University between July 2009 to July 2014 was analyzed.There were 37 patients received sentinel lymph node biopsy directly.And 39 patients received sentinel lymph node biopsy after a excisional biopsy to primary lesion.We compare the difference of detection rate of sentinel lymph node between the two groups.Results Seventy cases had been found sentinel lymph node successfully in a total of 76 patients and the detection rate is 92.1％.There were 34 cases had sentinel lymph node biopsy in successfully in group of excisional biopsy and the detection rate is 87.2％.There were 36 cases had sentinel lymph node biopsy in successfully in group of needle core biopsy and the detection rate is 97.3％.This difference,however,was not statistically significant between the two groups (P ＞ 0.05).Conclusions The influence of excisional biopsy on detection rate of sentinel lymph node biopsy through methylene blue in breast cancer is not significant.