A review of 1134 patients from the John Wayne Cancer Clinic with melanoma metastatic to regional lymph nodes was carried out to evaluate the importance of various prognostic features after lymphadenectomy. Univariate analysis identified the prognostic significance of clinical stage for lesions with a depth of 0.76 to 4.0 mm (p = 0.0018); number of involved nodes (p = 0.0001); Breslow's thickness (p = 0.0487); gender (p = 0.0103); location on an extremity (p = 0.0104); synchronous versus asynchronous detection of nodal metastases (p = 0.0107); age as a continuous variable (p = 0.0670); and unknown primary site (p = 0.088). Multifactorial analysis showed that number of involved nodes (p = 0.0001), extremity location of primary (p = 0.0059), and Breslow thickness (p = 0.0334) maintained their significance, whereas gender (p = 0.0627) and clinical stage (p = 0.0942) were almost significant. The long-term survival of the entire patient population at 5, 10, and 15 years of follow-up was estimated to be 46%, 41%, and 38%. When individual characteristics found to be significant by multivariate analysis were combined into different subsets, there was considerable heterogeneity, with 5-year survival varying from 79% to 14%. To quantify this heterogeneity better, a mathematical model was developed and found to approximate closely the observed survival rates in the heterogenous subsets and in the group as a whole.