BACKGROUND/AIMS: In western countries, symptomatic diverticulitis develops in about 20% of the population with colonic diverticula, and it is mainly located at the left-sided colon. The clinical characteristics of diverticulitis have rarely been investigated although its incidence is increasing in Asia including Korea. The aim of this study was to compare diverticulitis with asymptomatic diverticulosis and to compare the clinical characteristics of right-sided diverticulitis with those of left-sided diverticulitis. METHODS: We retrospectively investigated the medical records of the patients who had symptoms and signs of diverticulitis. Their diagnosis was confirmed with computed tomography, barium study, colonoscopy and/or operations at Samsung Medical Center from September 1998 to February 2002. The control cases of asymptomatic and incidental diverticulosis were randomly selected during routine health check-up after matching age and sex. RESULTS: Twenty-seven patients with diverticulitis (male : female=14 : 13) were included. The mean age was 53 (27~86). The ratio of right and left diverticulitis was 20:7, which was similar to the ratio of diverticulosis. The complications, especially perforation, were more frequent in the patients with left-sided diverticulitis (p<0.05). CONCLUSIONS: Colonic diverticulitis is more prevalent at the right colon and left colonic diverticulitis has more complications than right colonic diverticulitis in Korea.