Post-transplant lymphoproliferative disease (PTLD) is a serious complication after organ transplantation. We describe the case of a 45-year old patient who developed an EBV associated B-cell lymphoma in a cadaveric renal allograft. This case underscores the importance of considering PTLD as possible differential diagnosis for allograft dysfunction. Careful diagnostic evaluation should be undertaken in patients who present with risk factors for development of PTLD such as high doses of immunosuppression for rejection therapy, suspicious EBV serologies or negative EBV serologies before transplantation. PTLD can be of donor or recipient origin. Independent of its origin PTLD needs an immediate therapy which depends on the histology of the lymphoma and on the clinical conditions of the patient. Therapeutic options are reduction of the immunosuppression, chemotherapy or radiation, administration of lymphocyte-specific antibodies or removal of the kidney allograft.