Abstract: Objective:To explore the clinical value of ^99mTc-sulfur colloid (Sc) preoperative lymphoscintigraphy in senti-nel lymph node biopsy (SLNB) in breast cancer patients.Methods:Participants included70patients with breast cancer who underwent sentinel lymph node (SLN) detection with preoperative lymphoscintigraphy between July 2009 and January 2010. A dose of 37MBq ^99mTc-SC was hypodermically injected around the tumor at 3, 6 and 12o'clock positions on the breast. Lymphoscintigraphic images were taken at 15min, 30min, 1h, and 2h after hypodermic injection. Intraoperative de-tection of "hot spot" lymph nodes was performed with a handheld gamma probe ( γ-detection). Data from the breast cancer patients who received consecutive preoperative lymphoscintigraphy before SLNB in our database were analyzed.Results: Sentinel lymph nodes (SLN) were well imaged by lymphoscintigraphy in 60(85.71%) patients, and SLN were found in the extra-maxillary space in 5 patients (7.15%). The success rate of SLNB in lymphoscintigraphy was not associated with histo-pathologic type or the stage and location of the primary tumor ( P>0.05). However, the success rate of lymphoscintigraphy results was associated with the time interval between injection of radio colloid and surgery ( P<0.05). The success rate of surgical identification of axillary SLN was associated with the imaging of hot spots by lymphoscintigraphy (P<0.05). Conclusion: Preoperative lymphoscintigraphy in SLNB in breast cancer patients has significant clinical value. ^99mTc-SC has a better detection rate and guidance value in SLN detection of breast cancer. It is an effective guide for surgery and should be brought to the attention of clinicians.