Objective: Blue dye was one of the methods for sentinel lymph node biopsy in breast cancer, but the success rate was affected by multiple factors. This study was to determine the related factors contributing to the success of sentinel lymph node biopsy in breast cancer using blue dye method. Method:From Jan. 2007 to Aug.2008, sentinel lymph node biopsy was performed by periareolarly injecting 1% methylene blue in 141 breast cancer patients followed by axillary clearance. Pathological diagnosis was performed for all of the lymph nodes by conventional HE staining. Unconditional logistic regression was applied to make both univariate and multiva-riate analysis. Results:Sentinel lymph node was successfully detected in 126 patients. But the biopsy was failed in the 15 patients. The success rate was 89.4% and the false negative rate was 6.82%. Univariate analysis showed that success rate of biopsy was in association with patients' age, body mass index (BMI), tumor size, preoperative axillary node's status, pathological grade as well as ≥4 positive axillary lymph nodes involved. Multivariate analysis indicated that the patients'age (OR=4.587, P=0.024), BMI (OR=4.882, P=0.011) as well as 4 or more of the axillary nodes involved (OR=3.143, P=0.013) were independent predicting factors for the success of sentinel lymph node biopsy. Conclusions:Methylene blue dyeing is a reliable method for sentinel lymph node biopsy. The rate of success is associated with patients' age, BMI as well as the number of metastases in axillary lymph nodes.