Epstein-Barr virus (EBV), a virus of the human Herpes viridae class, has a particular importance in renal transplantation because of its complex interaction with the immune system. Indeed, it causes both infectious mononucleosis (IM), immunopathological responses of the host, and at the extreme a malignant tumor, when the responses are altered. The lymphoproliferative syndromes induced by the EBV infection are lymphoid proliferations resulting from the loss of an EBV-specific cytotoxic T-cell response. About 10% of B-type lymphoproliferative syndromes including diffuse large Bcell lymphoma are EBV-positive. We report the case of a 23-yearold man who developed a tumor in the nasal cavity 6 months after renal transplantation. His nephropathy was membranoproliferative glomerulonephritis. The induction therapy indicated was antithymoglobulin (ATG) and solumedrol. In maintenance therapy, mycofenolate mofetil (MMF) and tacrolimus were used. Nasal biopsy has proved CD20-positive B-cell lymphoma. No other site of the disease has been identified. The immunosuppressive agents were modulated with a switch of tacrolimus by an m-TOR inhibitor and a progressive reduction of MMF. After three cycles of R CHOP followed by radiotherapy, he achieved complete remission with a stable graft function.