BACKGROUND: Obesity and inflammatory bowel disease (IBD) represent chronic inflammatory conditions. Bariatric surgery improves some obesity-related co-morbidities, but the effects of bariatric surgery on IBD have not been well studied. OBJECTIVES: To examine if bariatric surgery may attenuate colitis in an obese murine model of IBD and study the mechanisms underlying the postsurgical amelioration of intestinal inflammation. SETTING: University of California Irvine, Department of Surgery and Microbiology laboratories. METHODS: Obese mice were assigned to one of 2 bariatric procedures [Duodenojejunal Bypass (DJB n = 6), Sleeve Gastrectomy (SG n = 8)]. Sham-operated mice were (Sham n = 8) were used as a control. After recovering from surgery, IBD was induced by administration of 2% dextran sodium sulfate. Fecal samples were collected before and after IBD induction for microbiome analysis. Pathologic analyses and immunohistochemical staining were performed on colon. RESULTS: Survival after DJB and SG was higher relative to Sham mice. Histologically, DJB mice had significantly less intestinal inflammation. The observed improvements were not related to a difference in weight among the groups. Farnesoid X receptor staining in the colon was observed quantitatively more in DJB than in SG and sham mice. A statistically significant increase in the number of Lactobacillales was observed in the stool of mice after DJB. CONCLUSION: These results suggest that bariatric surgery, in particular DJB, reduces the severity of colitis in a chemically-induced IBD murine model. The anticolitis effects of DJB may be associated with Farnesoid X receptor regulation and gut microbiome rearrangements. Copyright © 2017 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved.