Twenty-four patients with non-Hodgkin's lymphoma and CNS involvement are presented. There were 7 cases with diffuse histiocytic lymphoma (HL), 9 with diffuse poorly differentiated lymphocytic lymphoma (PDLL-D), of whom 6 patients were in leukemic conversion, 5 patients with nodular poorly differentiated lymphocytic lymphoma (PDLL-N), and 3 cases with undifferentiated lymphoma (UL). CNS complications were noted only in Stage IV lymphoma; the prognosis was generally poor. Histiocytic lymphoma was associated with widespread parenchymatous infiltration, whereas PDLL was usually associated with leptomeningeal seeding. The clinical course and the neuropathologic findings are discussed.