PURPOSE: Despite advances in surgery, antimicrobial therapy and postoperative intensive care, severe secondary peritonitis, caused by colonic perforation, remains a potentially fatal affliction. The appropriate surgical management of colonic perforation has always been a controversial issue, and one that continues to evolve. The differences in patient's characteristics, due to their medical problems, general conditions, peritonitis grade, or causes of perforation, influence both the surgical decision and the outcome. The aim of this study was to evaluate and compare the incidence, management and outcome of patients with different causes of non-traumatic colon perforation. METHODS: Between February 1993 and February 2002, 42 patients underwent emergency operations for non-traumatic colon perforations. We compared the morbidity and mortality with age, cause, perforation site, extents of peritonitis and surgical procedure. In patients with colorectal-cancer, we assessed the outcomes as perforation types; the perforation of the tumor itself, diastatic perforations proximal to an obstructing tumor and tumor stages. RESULTS: The causes of perforation were cancerous in 17 (40.5%), idiopathic in 7 (16.7%), diverticular in 5 (11.9%), colitis in 4 (9.5%), adhesion and strangulation in 4 (9.5%), stercoral in 3 (7%) and enema induced in 2 (4.8%). The morbidity and mortality in this study was high 76.2 and 26.2%, respectively. The morbidity and mortality was increased as the intra-abdominal fecal contamination increased (P<0.05). but there were no correlations between the complication rate, age, cause, perforation site or operation procedure. In patients with colorectal cancer, there were no correlations between the morbidity and mortality, perforation type or tumor stages. CONCLUSION: A non-traumatic colon perforation is associated with high morbidity and mortality. The prognosis of patients is determined by the grade of their peritonitis. Early diagnosis and prompt surgical management will result in better outcomes for patients with non-traumatic colon perforations.