Abstract BACKGROUND An excessive increase in the incidence of primary central nervous system lymphoma (PCNSL) has been reported since the mid‐1980s in the U.S. and U.K. Clinical studies have shown that radiotherapy and chemotherapy may prolong survival. In the current study, the authors describe the incidence, treatment, and survival of an unselected group of patients with PCNSL in the southern and eastern Netherlands. METHODS Data regarding patients diagnosed between 1989–1994 were obtained from 4 population‐based regional cancer registries in the southern and eastern Netherlands ( n = 86) and the Eindhoven Cancer Registry for 1980–1988 ( n = 6). Lymphomas were registered as PCNSL when a tissue diagnosis of CNS lymphoma was established for a patient with neurologic symptoms (i.e., lymphomas were not necessarily restricted to the CNS at the time of diagnosis). Only patients diagnosed during their lifetime with Stage I disease, Stage “IV” disease (i.e., diffuse CNS lymphoma), or disease of unknown stage were included (63 patients, 8 patients, and 15 patients, respectively, between 1989–1994). For 80 patients (93%) follow‐up was complete until January 1, 1997. RESULTS Between 1989–1994, an average World Standardized Rate of 2.3 cases and 1.7 cases per 1 million person‐years, respectively, was reported for males and females. The median age of the patients at the time of diagnosis was 62 years, and was 66 years for patients with an unknown disease stage. In the area of the Eindhoven Cancer Registry the occurrence of PCNSL more than doubled from < 2% of all histologically confirmed primary CNS malignancies diagnosed between 1980–1985 to approximately 4% of cases diagnosed between 1986–1994. The median survival of all the patients was 4.1 months; the median survival was 5.8 months for patients with limited (Stage I and Stage IV) disease and was 0.6 months for patients with an unknown stage of disease. Approximately 65% of the patients with limited disease received radiotherapy and approximately 35% of such patients ...