A case of suprasellar germinoma metastatic to the peritoneum 3 years after the placement of a ventriculoperitoneal shunt is presented. The excised metastatic germinoma was analyzed immunohistochemically with monoclonal antibodies against human lymphocyte subpopulations. Approximately 80% of the lymphocytes expressed pan-T, or Leu-1, surface antigens, and 20% were B1+, or B cells. Approximately 30% of T cells were Leu-2+, or cytotoxic and suppressor cells; 70% were Leu-3+, or helper cells. The large number of T cells is consistent with their role in cell-mediated immunity; their subpopulation ratio approximated that of the circulation. The literature pertinent to germinoma shunt metastasis is also reviewed.