INTRODUCTION: Lymphatic mapping and sentinel lymphadenectomy (LM/SL) is considered the nodal staging procedure of choice for patients with intermediate thickness (> 1.0mm, <4.0mm) melanoma. Despite this, the procedure has not been universally adopted. The aims of this investigation are to document the prevalence of LM/SL utilization and to identify predictors of under use. METHODS: All incident cases of melanoma from 1999-2001 reported to the North Carolina Central Cancer Registry (CCR) were examined. Subjects who had primary tumors >l.0mm and <4.0mm thick and no clinical evidence of nodal or distant metastases were considered eligible for LM/SL. Bivariate and multivariate logistic regression analysis was performed to identify factors associated with receipt of LM/SL. RESULTS: There were 3436 incident cases of melanoma reported for 1999-2001 (1111 in 1999, 1089 in 2000, and 1236 in 2001). 273 cases (8%) were excluded from analysis due to distant metastases or palpable adenopathy. An additional 916 29%) cases were excluded because the T classification of the primary tumor was not reported. Of the remaining 2247 cases, 1242 (55%) were eligible for LM/SL (T2 or T3), of which 48.0% (596/1242) underwent LM/SL. The proportion of subjects undergoing LM/SL was significantly associated with year of diagnosis (44% in 1999, increasing to 52% in 2000 and 50% in 2001, p=0.05). Subjects 60 years and older were less likely to undergo LM/SL compared to subjects less than 60 years (39% vs. 55%, p<0.001 ). Subjects with head or neck primary tumors were significantly less likely to undergo LM/SL compared to subjects with trunk or extremity primaries (32.9% vs. 51.4% and 51.9%, respectively, p<0.001), and subjects with T2 lesions were less likely to receive LM/SL than subjects with T3 lesions (41.7% vs. 53.6%, p<0.001). All of the associations remained statistically significant on multivariate analysis. CONCLUSION: Half of all eligible melanoma patients in North Carolina are failing to receive LM/SL. Predictors of underutilization of LM/SL include thinner primary tumors, advanced age, and head/neck location of the primary tumor. Further investigation is warranted to explore these differences and to improve utilization.