T-cell lymphoma may involve the CNS as either a primary or secondary neoplasm. This report describes 8 patients with either primary or secondary T-cell malignancies in the CNS. Five patients presented with symptoms and signs of CNS disease that included seizures, visual impairment, cranial nerve palsies, sensory and motor deficits, gait ataxia, and paraparesis. Three of them had primary parenchymal CNS lymphoma, and 2 had epidural lymphoma that originated in adjacent bone marrow. Three patients were neurologically asymptomatic, but had leptomeningeal tumor and focal parenchymal infiltration at postmortem examination. Histologically, 4 lymphomas were large cell, 3 were mixed large and small cell, and 1 could not be classified by the working formulation for non-Hodgkin's lymphomas. The clinical and pathologic manifestations of T-cell lymphoma in the CNS may be diverse. This report demonstrates that neurologic abnormalities may be the presenting signs of either primary CNS or systemic T-cell lymphoma.