Cutaneous melanoma first metastasizes into sentinel lymph nodes that control the lymphatic drain from the area of the primary tumor. This observation is used clinically for melanoma patients with primary melanomas thicker than 1mm (tumor stage T2a), for these patients sentinel lymph node biopsy has become an important and routinely performed diagnostic procedure. The importance of sentinel node analysis is reflected by a significant better prognosis of melanoma patients with tumor free sentinel nodes compared to patients with metastatic sentinel nodes. Although intensively studied, not much is known about mechanisms responsible for the development of melanoma metastasis.To analyze gene expression in mouse SLNs of M24met tumor bearing animals as compared to tumor free control animals, SLNs were taken at different time points and analyzed for the presence of human M24met to classify SLNs into control, negative, macro metastatic SLN. After categorized SLNs were subjected to microarray analysis.