PURPOSE: The present study was performed to assess the outcomes in patients with colonic perforation and to determine the prognostic factors for mortality. METHODS: The cases of 42 patients who underwent surgery for colonic perforation between March 1999 and September 2008 were retrospectively reviewed. Age, sex, American Society of Anesthesiologists (ASA) classification, presence of preoperative shock, duration of symptoms, cause of perforation, location of perforation, degree of peritonitis, and the Mannheim Peritonitis Index (MPI) score were analyzed for their association with early outcome by using univariate and multivariate analyses. RESULTS: Diverticulitis (46%, 19 patients) and colorectal cancer (36%, 15 patients) were the most common causes of noniatrogenic colonic perforation, and the sigmoid colon was the most common site of perforation (60%, 25 patients). The postoperative mortality was 21.4% (9 patients). The mortality in patients with preoperative shock, with a MPI score of more than 25, and with Hinchey stage III or IV peritonitis were 70.0%, 57.1%, and 53.3%, respectively (P<0.001). No statistical difference was observed in postoperative mortality with regard to age, sex, ASA classification, duration of symptoms, cause of perforation, and location of perforation. According to the multivariate analysis, preoperative shock proved to be the only significant prognostic factor for mortality (P=0.027) (odds ratio: 19.8, 95% confidence interval: 1.4-276.9). CONCLUSION: Preoperative shock, a MPI score of more than 25, and Hinchey stage III or IV peritonitis were associated with high postoperative mortality in patients with colonic perforation. Especially, more intensive management and interest are required for patient s with preoperative shock due to colonic perforation.