BACKGROUND In the last years many therapeutic attempts were made to improve the poor prognosis of primary cerebral non Hodgkin's lymphoma. The aim of this study was to report on own experiences concerning this rare disease. METHODS In 1986 to 1994 26 patients were treated for primary cerebral non Hodgkin's lymphoma. 15% were HIV-positive. High-grade non-Hodgkin's lymphomas were diagnosed in 62%. 46% of all cases showed multiple lesions. 23% of our patients received a dose less than 25.5 Gy, 27% received 37.5 Gy (whole brain) and 39% were treated with 51 Gy (37.5 Gy whole brain and 13.5 Gy boost dose). Radiation technique included regular and irregular fields (single dose: 1.5 Gy). RESULTS 62% of patients achieved a complete or partial remission directly after irradiation, in 4% no change or progression was seen. 31% could not be examined due to their bad status or death. The mean follow-up time for all patients was 19.6 months, the median survival was 3.6 months. The 1-year-survival rate was 41%, 3-year survival rate was 28%. Patients who received a tumor dose of 51 Gy had better survival times in comparison to patients who received less (p = 0.01). Prognostic parameters (Cox regression analysis) were: tumor dose, grading and local result after irradiation. The Karnofsky performance status was not an independent parameter (p = 0.12). Side effects were low. Long-term survivors had relatively good quality of life. CONCLUSIONS Taking into consideration the small numbers of patients in all studies all results or conclusions have to be made with great reservations. Despite the high proportion of HIV-positive patients our results are in compliance with other authors using similar therapy protocols. Reports dealing with combined radio-chemotherapy have published good results concerning survival time. But long-term morbidity due to these protocols needs further investigation and has to be awaited.