This paper reports on 10 patients (4 male, 6 female) with primary non-Hodgkin's lymphomas of the brain (CNS-NHL--mean age 46.8 years, mean postdiagnostic survival 10 months). Pathological CSF (cerebrospinal fluid) was found in all 8 patients examined (positive cytology in 7/8 cases). Solitary tumors, diffuse periventricular infiltration or diffuse cerebral infiltration were demonstrated in cerebral computer-assisted tomography (CAT). Angiographical findings were unspecific. The histologic subtypes were lymphoplasmacytoid immunocytoma (4), unclassified low grade (1), centroblastic (1), B-immunoblastic (1), T-immunoblastic (1), lymphoblastic convoluted T-cell type (1), unclassified high grade (1) NHL. Patients who had received radiotherapy (+/- surgery) in this group had a mean survival of 15.66 months (sigma = 7.63). In addition, an overview of 83 well-documented, cases of the literature tries to characterize main histological and topographical distributions, histology-, patient's age-, and therapy-related survival. Patients with primary CNS-NHL have a 5-year survival expectancy of 30% compared with 2.3% in secondary CNS-manifestations of systemic non-Hodgkin's lymphomas. In this report, the beneficial effect of radiotherapy (mean survival 30.3 months) compared to surgery or symptomatic treatment (3.6 or 3.3 months) could be confirmed. It is concluded that primary CNS-NHL frequently present with atypical neuropsychiatric syndromes; diagnosis should be established preferentially with CAT and CSF-examinations or stereotactic biopsies, whereas open surgery should be avoided. An approach to exact classification should be attempted, as survival is clearly related to histological subtypes.