Rituximab has been associated with the development of cytomegalovirus enterocolitis in immunosuppressed patients. A 51-year-old patient with diffuse large B-cell lymphoma who received a conditioning chemotherapy regimen (RCVP and RICE) consisting of rituximab before bone marrow transplantation went on to develop cytomegalovirus enterocolitis. This supports evidence from previously described cases that rituximab may be associated with cytomegalovirus enterocolitis.