BACKGROUND/AIMS: Recently, it has been well known that the incidence of colonic diverticulosis is increasing in Korea. However, cases of right-sided colonic diverticulitis are rare although diverticula are located in right-sided colon more than left-side. The major clinical symptom of right-sided colonic diverticulitis is acute right lower quadrant pain which may mimic acute appendicitis. Therefore, we evaluated the clinical characteristics of the patients with right-sided colonic diverticulitis and safety of the colonoscopic examinations in these patients. METHODS: The evidence of diverticulitis was confirmed by the presence of pus at the diverticular lesions on colonoscopy. We retrospectively analyzed clinical menifestations, laboratory findings, colonoscopic findings and the presence of complications after colonoscopy, and radiologic findings of the patients with right-sided colonic diverticulitis. RESULTS: All the patients with right-sided colonic diverticulitis had abdominal pain. Physical examinations showed abdominal tenderness in all patients and leukocytosis was noticed in 8 out of 12 patients (66%). There was no complication during and after colonoscopy. All the patients were managed with conservative treatment including broad-spectrum antibiotics and improved without clinical aggravation. CONCLUSIONS: The colonoscopic examination may be helpful to diagnose right-sided colonic diverticulitis.