A symptomatic cytomegalovirus (CMV) infection usually occurs in patients with debilitating diseases, immunosuppression, transplantations and acquired immunodeficiency syndrome (AIDS). Gastrointestinal infections with CMV, especially colitis, are usually found in immunocompromised patients and rarely affect immunocompetent subjects. Here we report the case of a young female patient with a history of ulcerative colitis (UC) who presented with an acute attack of colitis caused by CMV infection. This was documented by the presence of CMV early antigen, antibodies and evidence of CMV in the colonic mucosa. After combined anti-inflammatory and antiviral treatment the patient recovered completely. As most attention is given to CMV-pathogeneity in immunocompromised patients, here we discuss the relationship to inflammatory bowel diseases.