Background.Non-Hodgkin’s lymphoma is the second most frequent neoplasia following solid-organ transplantation. The objective of this study is to describe the clinical, histologic, and radiologic features of primary posttransplantation brain lymphomas (PTBL) in addition to their outcome.Methods.Twenty-five kidney transplant patients with histologically proven PTBL from 11 French centers were retrospectively investigated.Results.Immunosuppressive regimen included induction with antithymocyte globulins (ATG) in 20 patients. Median overall delay between transplantation and lymphoma was 18 months (4–264). Six of 10 patients with late posttransplantation brain lymphomas (PTBL) occurrence (>3 years) had been recently switched from azathioprine to mycophenolate mofetil (median switch lymphoma delay 14 months). Cerebral computed tomography (CT) scans and magnetic resonance imaging (MRI) revealed multifocal lesions (n=18), with a ring contrast enhancement (n=20) similar to cerebral abscesses, as observed in HIV-related brain lymphomas. Histology showed large B-cell non-Hodgkin’s lymphoma in 87.5% of cases; Epstein-Barr virus (EBV) was detected in 95%. After lymphoma diagnosis, immunosuppressive treatment was reduced in all patients, and all but one received complementary treatment by surgery (n=2), anti-CD21 antibodies (n=2), chemotherapy including high-dose intravenous methotrexate (n=7), encephalic radiotherapy (n=5), or chemotherapy plus radiotherapy (n=8). Median overall survival was 26 months. Patients with a radiotherapy-based regimen seemed to have a longer survival (36vs.7 months,P<0.005).Conclusions.Our study showed that PTBL are EBV-induced large B-cell lymphomas, which mimic cerebral abscesses on imaging and whose occurrence may be influenced by immunosuppression modifications. Treatment by radiotherapy is associated with better survival.