Sentinel lymph node (SLN) identification by lymphoscintigraphy (LS) and biopsy are the standard method for axillary lymph node staging in low stage breast cancer patients. Many previous studies did not compare the number of SLN on LS with SLN detected during surgery. We aimed to study the accuracy of pre-operative LS for the prediction of the number of SLN detected by surgical gamma probe and the dye technique during surgery. Sixty patients were included in our study. SLN biopsy was performed using the combined radioactive and blue dye methods. Patients without previous excisional biopsy of the tumor (45 patients) received periareolar intra-dermal injections of 17.5MBq/0.2mL technetium-99m-antimony sulfide colloid ((99m)Tc ASC). The remainder of the patients, with the history of excisional biopsy of the tumor (15 patients); received two intra-dermal injections of 17.5MBq/0.2mL (99m)Tc-ASC in both ends of the surgical incision. All injections were done 2-4 h before surgery and gentle massage was applied to the injection site. Results showed that the number of SLN was correctly detected by LS in 58 patients. Eighty SLN were totally detected during surgery. All these SLN were radioactive and could be identified by surgical gamma probe. No SLN was detected only by the blue dye. Of the 80 detected SLN, 60 (75%) were both radioactive and colored. Pre-operative LS correctly predicted the number of harvested SLN during surgery in 77.5% of the patients. Only 78.7% (63/80) of the total harvested SLN were detected by pre-operative LS. We conclude that pre- operative LS identifies 78.7% and the blue dye technique can identify 75% of the SLN found by the gamma probe during surgery. The pre-operative LS technique can correctly identify the number of SLN in 77.5% of the patients.