A rare case of hemorrhagic malignant melanoma from an unknown primary origin to the right sphenoid bone in a 37-year-old woman is presented. The tumor occupied an extensive intracranial extradural space with a mild orbital infiltration, but little involvement of the leptomeninges and parenchymal tissues. Immunohistochemical analysis of the tumor-infiltrating lymphocytes showed that the majority expressed pan-T or Leu-1 surface antigens and that the lymphocytes bearing the Leu-3 antigen, or helper phenotype, were predominant compared to the Leu-2 population representing both suppressor and cytotoxic T cells. Furthermore, most of the T lymphocytes stained with HLA-DR antigens. Because few B cells were seen, this observation indicates the presence of T cells in an activated state. The literature pertinent to associated organ involvement of metastatic melanomas and the correlations between the tumor and immunological cellular responses are discussed.