Meningeal involvement (MI) by non‐Hodgkin's lymphoma (NHL) was seen in 38/602 patients (6.3%). In relation to histologic subtype the frequency of MI was: Follicular small cleaved and mixed cell 2/128 (1.6%), small lymphocytic and diffuse small cleaved cell 2/83 (2.4%), large cell and immunoblastic 13/295 (4.5%), small noncleaved cell 6/31 (19%), lymphoblastic 15/66 (23%). Risk factors that predict for MI were, besides histologic subtype, age under 40 yr, clinical stage IV, site of involvement (bone marrow, bone, skin gastrointestinal tract), and a poor response to initial therapy. In a Cox multivariate model encompassing the intermediate and high grade malignancy groups of the Working Formulation (WF), the 3 most important risk factors were histology, age, and stage. The estimated 1‐yr probability of MI for combinations of the 3 risk factors was: 3 risk factors (61 %), 2 risk factors (15–28%), 1 risk factor (4–8%), 0 risk factor (1.5%). At the diagnosis of MI, 84% of the patients had evidence of advanced systemic NHL, and the median survival after MI was 10 wk. CNS prophylaxis with whole‐brain irradiation and intrathecal chemotherapy can only be recommended in patients with 2 or 3 risk factors. Improvement of the systemic chemotherapy might be the most important factor for prevention of MI in NHL.