['Sentinel lymph node biopsy (SLNB) is standard practice for intermediate-thickness head and neck melanoma (HNM) but remains controversial for melanomas more than 4 mm in thickness. The objectives of this study were to evaluate (1) the diagnostic accuracy and (2) the prognostic value of SLNB in patients with thick HNM.', 'Case series with chart review.', 'Large cancer center between June 2000 and December 2012.', '77 patients undergoing SLNB for T4 HNM without in-transit, regional, or distant metastatic disease at presentation.', 'Univariate and multivariate analyses of prognostic factors were performed.', '77 patients underwent attempted SLNB for T4 HNM without in-transit, regional, or distant metastatic disease at presentation. The mean patient age was 62 years (range, 4-87 years) and there was a male predominance (80%). Mean Breslow thickness was 6.1 mm (range, 4-21 mm). Of the 77 patients undergoing attempted SLNB, 7 had no identifiable sentinel lymph node (9%). For the remaining 91% with 1 or more identifiable sentinel lymph nodes, the mean number of nodes identified was 3.3 (range, 1-13). The sentinel lymph node positivity rate was 24%. A false-negative SLNB occurred in 2 patients (3.8%). With a median follow-up of 36 months, the estimated 5-year disease-free, disease-specific, and overall survival rates were 47%, 74%, and 69%, respectively. A positive sentinel lymph node was significantly linked to shortened disease-free survival (74 vs 36 months, P = .026) and disease-specific survival (121 vs 59 months, P = .035).'] Does sentinel Lymph Node Biopsy provide Prognostic Value in Thick Head and Neck Melanoma?