From January 1993 to May 2000, 1062 patients with primary cutaneous melanoma and no evidence of clinically detectable regional node metastases underwent sentinel node (SN) dissection to microscopically define the tumor status of the regional lymph nodes. A total of 1165 biopsies were performed. The SN identification rate was 89.6%. In 62.2% of the cases, only one SN was detected; 26.4% of patients had two SNs; and 11.4% had three or more SNs. Analysis of survival indicated that the tumor status of the nodes was the most important prognostic factor. Breslow's thickness had a significant impact on survival in tumors 4 mm or thicker, and ulceration dropped to a borderline-significant P value. To assess the tumor burden in positive SNs, all slides for patients at the Istituto Nazionale Tumori and S. Pio X Hospital were reviewed. Of 658 patients in this series, 90 had positive SNs. Eighteen of these patients had evidence of metastasis in other nodes. Of the remaining 72 with a single tumor-involved SN, 62% had a single metastatic deposit. Preliminary data from this study indicate that several subgroups may be identified among patients with positive nodes, but adequate analysis of survival requires a larger number of patients and a multicenter study.