Background: Mechanical intestinal obstruction, characterized by bowel distension, hypersecretion and altered motility, is one of the most common admissions for acute abdominal conditions. Although the underlying mechanisms leading to these physiologic derangements have been proposed to be associated with the interactions between intestinal microflora and mucosal cells, the role of another potential mediator, bile, has not been well identified. This study was aimed to delineate the role of bile in the pathogenesis of acute simple mechanical bowel obstruction. Materials and methods: Forty-two Sprague-Dawley rats were randomized into 6 groups and subjected to different treatments: Group 1, sham operation; Group 2, complete ileal ligation (IL) at 20 cm to the cecum; Group 3, IL followed by common bile duct ligation (CBDL); Group 4, IL + CBDL followed by external drainage (ED); Group 5, IL + CBDL followed by CBD-urinary bladder diversion (UBD); Group 6, IL + CBDL followed by bile diversion to the ileum distal to the obstruction. All rats were sacrificed 2 days after operations. The bowel distension, fluid accumulation, superoxide anion production and the histopathological alterations in the obstructed intestines were measured. Results: Ileal ligation resulted in marked bowel distension, copious fluid secretion and free radical production as compared to the sham group. These effects were significantly attenuated by CBD ligation or CBD ligation with bile diversion to either outside the body or urinary bladder. In contrast, no such beneficial effects were observed in the group of IL + CBDL with bile diversion to the ileum. Histopathological examinations revealed that bile deprivation from the obstructed intestinal segment did not affect the obstruction-induced mucosal damage. Also, there was no significant correlation between the extent of mucosal injury and the magnitude of fluid secretion or superoxide anion production. Conclusion: Bile is partially responsible for the observed manifestations of acute simple mechanical intestinal obstruction, probably through both direct and indirect mechanisms.