Abstract Background: Determination of axillary nodal status is essential for the staging of breast cancer since nodal status is one of the most important predictors of survival. The objective of this study was to test the hypothesis that the histology of the first draining lymph node (LN) accurately predicts the histology of the rest of the axillary LNs. Methods: Fifty-five patients with operable invasive breast carcinoma and clinically negative axillary lymph nodes were studied. Patients were injected with Technetium-99 ( 99Tc) sulfur colloid around the primary tumor. A hand-held gamma detector probe was used to identify the sentinel LN (SLN). After the SLN was identified and removed, a level I and II lymphadenectomy was performed. Results: The SLN was identified in 53 (96.3%) of the 55 patients entered into the trial. The sensitivity was 88.2% and the specificity was 100%. The positive predictive value was 100% and the negative predictive value was 94.6%. The accuracy of the study was 96.2%. Conclusions: The SLN biopsy for breast cancer staging is highly accurate in our hands and has the potential to decrease the morbidity and cost of managing patients with breast cancer without compromise of staging.