Posttransplant lymphoproliferative disorder (PTLD) is a serious complication of organ transplantation. PTLD is the disorder arising from the combined effects of Epstein-Barr virus associated lymphoid proliferation with the disruption of the normal immune control by the cytotoxic T cells. The treatment for PTLD is one of the most controversial topics in solid organ transplantation. It is well known that the initial management of PTLD is a reduction of immunosuppression. Early diagnosis and the early reduction in immunosuppression are essential even for monomorphic lymphoma. We report here on a case of the complete resolution of PTLD (diffuse large B cell lymphoma) which occurred after a drastic reduction of immunosuppression in a renal transplant recipient.