Cytomegalovirus infections in immunocompromised patients may cause serious illness, particularly in patients with HIV-disease and in transplant recipients. There is an increasing number of reports of cytomegalovirus infections involving the alimentary tract, especially colitis. Diagnosis of cytomegalovirus disease is at present based on specific histological findings. Antibody findings can be difficult to interpret. The slow growth of cytomegalovirus in cultures makes this method less useful in the acute setting of diagnosis. It is important to recognize cytomegalovirus colitis as a differential diagnosis to idiopathic inflammatory bowel disease. In fulminant disease, colectomy should be considered in addition to antiviral treatment.