Posttransplant lymphoproliferative disorder is a serious, life-threatening complication in organ transplant patients receiving immunosuppressive therapy. Isolated posttransplant lymphoproliferative disorder of the gastrointestinal tract is rare. Posttransplant lymphoproliferative disorder encompasses a spectrum of clinical manifestations, in addition to a wide range of histopathological findings, from B-cell hyperplasia to lymphoma. Renal transplant patients with small intestinal posttransplant lymphoproliferative disorder are more likely to be of younger age, but less frequently represent Hodgkin and Hodgkin-like lesions. They also have better patient survival compared with transplant recipients with posttransplant lymphoproliferative disorder in other locations. We report on the treatment of a kidney transplant recipient with confirmed isolated posttransplant lymphoproliferative disorder in the small intestine. The patient presented with acute abdomen and small intestine perforation, 17 years after kidney transplant, despite being without calcineurin inhibitor in immunosuppressive therapy, to mitigate previous ductal breast carcinoma. Pathological examinations revealed isolated EpsteinBarr virus-positive diffuse large B-cell non-Hodgkin lymphoma of small intestine, clinical stage IV A E. The patient was treated with reduction of immunosuppression, rituximab, and the CHOP regimen (ie, cyclophosphamide, doxorubicin, vincristine, and prednisone). A complete remission was achieved. Kidney allograft function was stable throughout the follow-up period. Physicians should consider isolated gastrointestinal posttransplant lymphoproliferative disorder as a possible etiology in posttransplant, immunocompromised patients who present with different gastrointestinal symptoms. Given good clinical response to treatment, early identification of posttransplant lymphoproliferative disorder has a key role in monitoring and treatment.