A 42-year-old woman underwent renal transplantation in 200X. After the transplant, she received tacrolimus as immunosuppressant therapy. Eleven years after the transplant, diffuse large B-cell lymphomas were detected in the duodenum and terminal ileum. Wireless capsule endoscopy (WCE) revealed multiple lymphoma lesions in the entire small intestine. The patient achieved complete response through the administration of R-CHOP therapy and discontinuation of immunosuppressant therapy. Post-transplant lymphoproliferative disorder (PTLD) is a rare complication and WCE may be useful for diagnosing PTLD of the small intestine.