A 22-year-old male who had received a kidney transplant from his father (HLA haploidentical), presented with fever and malaise. After transplantectomy was performed because of rejection, the patient developed abdominal pain due to perforation of the small intestine. Non-Hodgkin's lymphoma was found in both the transplant and the small bowel. The patient had suffered a primary Epstein-Barr virus (EBV) infection, probably transferred through the transplanted kidney. DNA analysis showed that the lymphoma was of patient origin. After withdrawal of immunosuppressive therapy, no recurrence of the lymphoma was seen. EBV is a well-known aetiologic agent of non-Hodgkin's lymphomas arising in the immunocompromised patient.