A retrospective analysis of 12 patients with primary central nervous system non-Hodgkin's lymphoma seen from 1958 to 1980 was carried out with emphasis on diagnostic evaluation and treatment results. Computerized tomography (CT) scans were found to be the most valuable diagnostic tool both for initial evaluation as well as follow-up. Characteristic CT scan features were identified and are discussed. Three patients had a history of previous immunosuppression; two had preceding and concurrent uveitis. Nine of the 12 patients were treated primarily with radiation therapy. Three patients were diagnosed at autopsy and had not received definitive therapy. Size of lesion proved to be the most important prognostic factor and appeared to be related to location. Gross total excision of tumor did not appear to improve survival. Two patients were alive with no evidence of disease at 38 and 48 months, respectively. Recurrences were noted from 1 to 33 months after diagnosis (median, 14 months), suggesting the advisability of long-term follow-up prior to presumption of cure. From these results and a review of the literature, possible treatment approaches are presented.