OBJECTIVE Sentinel lymph node (SLN) biopsy has shown great utility in the management of melanoma. An analysis of regional recurrence in previously mapped negative SLN basins as the first site of relapse is performed. METHODS A retrospective query of a prospective melanoma database from 1994 to 2006 identified 1287 patients who underwent successful SLN biopsy. One thousand sixty patients (82.4%) were SLN negative and 227 (17.6%) patients SLN positive. Clinical variables were examined for the impact on regional recurrence by multivariate analysis. RESULTS Mean follow-up was 44.3 months (range 3-155 months). Thirty-five patients (3.3%) presented with false-negative (FN) SLN biopsy. Pathologic review of the SLNs harvested from these basins found 7 (20.0%) samples positive for metastatic melanoma. Multivariate analysis found head and neck site [hazard ratio 3.67; 95% confidence interval (CI), 1.77-7.60, P < 0.001] and tumor thickness (hazard ratio 1.16; 95% CI, 1.04-1.30, P = 0.01) to be predictive of FN SLN biopsy. The 5-year melanoma specific survival calculated from the date of the SLN biopsy was 57.6% (95%CI, 35.7-41.9) in the FN group, which was not statistically different than the SLN positive group 60.0% (95% CI, 29.6-40.1; P = 0.14). CONCLUSIONS Head and neck tumor site and tumor thickness are predictors of a FN SLN biopsy. Mechanisms other than pathologic SLN sampling error may contribute to the failure of the SLN biopsy in some patients. Patients with regional recurrence after negative SLN biopsy have a similar 5-year survival compared with patients with positive SLNs.