Clinical manifestations of Salmonella infection are variable such as enterocolitis, bacteremia, enteric fever, focal infection and asymptomatic carrier status. Among these presentations, enterocolitis is the most common clinical manifestation and can be diagnosed by the use of fecal specimens. Patients with severe infectious colitis are at increased risk of developing a colon perforation after colonoscopy due to colon trauma. We report a case of a 31-year-old woman with transverse colon perforation after colonoscopy that was diagnosed with enterocolitis caused by infection with non-typhoidal group D Salmonella. (Korean J Gastrointest Endosc 2008;36:395-400)