<p> A 58-year-old woman with a history of chronic myelogenous leukemia, for which she was taking dasatinib, was admitted to our hospital with diarrhea and bloody stool. Colonoscopic examination showed multiple protruding polyps with white exudates at the top in the ascending and transverse colon. Biopsy specimens showed erosions with exudates on the surface of the mucosa and intranuclear inclusions. Immunostaining with cytomegalovirus (CMV) antigen was positive. Endoscopic and pathological features suggested cap polyposis (CP) with CMV colitis. The patient was treated with ganciclovir and her symptoms quickly improved. CP is a rare colorectal disease characterized by multiple inflammatory polyps covered with a cap of fibrinopurulent exudates. The etiology of this disease remains unknown and there is no specific treatment. We report this rare case with a review of the literature.</p>