The past decade transplants of human tumors in nude mice have been increasingly used as an experimental model for local tumor growth and dissemination. A few human melanoma cell lines have been described that give rise to metastases in nude mice after subcutaneous inoculation. First we give an overview of some relevant literature with respect to the pathogenesis of tumor metastasis, models to study human cancer metastasis, neoplastic progression and the detection of antigens involved in metastasis. Finally we describe our results concerning the morphological and immunohistochemical profile of six different human melanoma cell lines and their xenograft lesions in nude mice using a set of monoclonal antibodies recognizing different categories of human melanoma-associated antigens. From the data we conclude that the nude mouse mouse model appears suitable to study the role of melanoma-associated progression markers in the pathogenesis of metastasis.