PURPOSE: Colonic diverticulitis is an uncommon disease in Korea, but the incidence of the disease is increasing. The right colon is the more preferred site for diverticulitis in Korea, but the incidence of left diverticulitis is increasing. Therefore, comparing the clinical features and treatments for right diverticulitis with those for left diverticulitis may help us to treat the disease more properly. METHODS: This study was performed retrospectively by reviewing the medical records of 96 patients with colonic diverticulitis, in whom either conservative or operative treatments were performed. RESULTS: Eighty-six patients had right diverticulitis (RD), and 10 patients had left diverticulitis (LD). The mean age of the patients was older for LD. Sixteen patients (18.6%) with RD had complications, and 7 patients (8.1%) underwent operations. On the other hand, 4 patients (40%) with LD had complications, and 3 patients (30%) underwent operations. The rates of complications and operations among old-aged patients were higher. The operations for 7 patients with RD who underwent surgery were 6 ileocecectomies and 1 diverticulectomy. On the other hand, the operations for the 3 patients with LD who underwent surgery were 2 resections and anastomoses and 1 diverticulectomy. The reasons for the operations were abscess formation, recurrence, perforation, and development of generalized peritonitis without response to conservative treatment. CONCLUSION: The incidence of LD is lower than that of RD in Korea, but the rate of complications and operations seems higher in LD. Therefore, patients who complain of left lower abdominal pain need to be thoroughly examined for LD.