Gliomatosis cerebri (GC) is a rare disease, defined as a diffuse neoplastic glial cell infiltration of the brain. Diagnosis and management of GC are difficult. This study analyzed 296 individual cases (90 patients followed through the ANOCEF network, and 206 cases from the literature), aged 1 month to 85 years (median 42), sex ratio=1.31. Median survival was 14.5 months. It was higher for patients younger than 42 years (17 months vs. 13 months), with performance status>or=80 (27 months vs. 9 months), low grade gliomatosis (grade 2=20 months, grade 3=11.5 months, grade 4=8.5 months), oligodendroglial subtype (36 months compared to 14 months for mixed GC and 11 months for astrocytic GC). Male population was younger (median 39 years vs. 45), had a higher incidence of oligodendroglial GC (22% vs. 13%), which may explain their better prognosis (median survival 17 months vs. 11.5 months) than female population. Despite a high rate of stabilization, the impact on survival of whole brain radiotherapy, which carries the risk of severe toxicity, is still unclear. Up-front chemotherapy benefit to some patients and may be preferred to whole brain radiotherapy. However, the many bias of such retrospective heterogeneous data claim for multicentric clinical trials in this rare disease.