This paper describes 2 immunocompetent patients with cytomegalovirus colitis and reviews all previously reported cases (n = 13). Affected patients were generally older (69.13+/-15.62 y-old) with probable reactivation (n = 8) or younger (43.86+/-19.73 y-old) with probable primary infection (n = 7). The onset of illness was found to be hospital-associated in 4 (50.0%) reactivation cases and 1 (14.3%) primary case. Presenting manifestations included diarrhoea (86.7%), fever (80.0%), gastrointestinal bleeding (66.7%) and abdominal pain (60.0%). Endoscopy showed erosive colitis with multiple (n = 11; 73.3%) or single ulcers (n = 2, 13.3%); biopsy was diagnostic in 12/13 (92.3%) patients. Complications included massive haemorrhage (13.3%), toxic megacolon (13.3%), perforation (13.3%) and protracted inflammatory bowel disease (20.0%; exclusively in primary-infection). The mortality rate was 26.7%. Antiviral-agents were given in 8 (53.3%) cases; assessment of treatment-efficacy was not possible. In conclusion, cytomegalovirus colitis in the immunocompetent-host is a rare but potentially severe erosive disease with significant morbidity. It may occur during primary infection or reactivation; the diagnosis requires careful histopathological examination and the benefit of antiviral-therapy is unknown.