In this retrospective study (1986-1996), a series of 250 immunocompetent patients (SFNC series) with primary malignant lymphoma of the central nervous system is reviewed and the lymphomas redefined using the REAL (Revised European-American classification of Lymphoid neoplasms) and the modified Kiel classifications. All the tumors available for review were classic diffuse non-Hodgkin's lymphomas. Thirty-eight were unclassifiable due to small size and artifacts in the specimens. Eight cases were of T-cell type (3.7%). The 212 others cases were B-cell type. According to the REAL classification, the high majority was diffuse large cell (62%). Following the modified Kiel classification percentage of cases categorized as low and high grade of malignancy were 22.4% and 77.6% respectively.