BACKGROUND AND AIM: This study compared the effectiveness of Tc-99m human polyclonal immunoglobulin (HIG) and Tc-99m nanocolloid at detecting sentinel lymph nodes (SLNs) with lymphoscintigraphy and an intraoperative gamma-probe (IGP) in patients with early breast cancer. METHODS: The study group consisted of 50 women; 25 patients each were given Tc-99m HIG or Tc-99m nanocolloid for lymphoscintigraphy. Then, intraoperative SLN localization with IGP was performed. The results of IGP, lymphoscintigraphy, blue dye injected just before surgery, and pathology were compared. RESULTS: In the Tc-99m HIG group, one patient had tumours in both breasts. In two patients, we could not detect SLNs with lymphoscintigraphy, although they were detected with IGP and blue dye. We found SLNs for all tumours with IGP. With the intraoperative blue dye, SLNs were identified for 25 tumours; for one tumour, no SLN was detected with blue dye. In the histopathological examination, 13 tumours showed metastasis in the SLN and in 11 of these 13, there were also metastases in the axilla. One patient had a skip metastasis. In the Tc-99m nanocolloid group, SLNs were identified in 24 patients with lymphoscintigraphy. IGP found SLNs in 24 patients. The blue dye detected SLNs in all patients. On histopathological examination, 10 patients had metastasis in the SLN and there were also metastases in the axilla in all of these patients. CONCLUSION: Tc-99m HIG can be used in SLN detection with preoperative lymphoscintigraphy and IGP in early-stage breast cancer patients.