Cytomegalovirus(CMV) disease is a major cause of morbidity and mortality in immunocompromised patients. CMV enteritis should be considered when nausea and vomiting continue 3 to 4 weeks after bone marrow transplantation(BMT). The treatment of CMV enteritis is not well established. We report a CMV duodenitis patient following allogenic bone marrow transplantation. The patient had prolonged nausea and vomiting for 5 weeks after bone marrow transplantation and CMV duodenitis was diagnosed by the gastroduodenoscopic mucosal biopsy which showed cytomegalic cells. Ganciclovir treatment for 3 weeks resulted in the resolution of symptoms and promoted healing of the lesion. The patient was free of CMV infection until 288 days after allogenic BMT without maintenance ganciclovir treatment.