Background: Obesity is becoming more prevalent in patients with inflammatory bowel disease. Although bariatric surgery is an effective treatment for obesity, questions remain regarding its safety and effec-tiveness for patients with inflammatory bowel disease. The aim of this study was to evaluate the safety and effectiveness of bariatric surgery in patients with inflammatory bowel disease. Method: This registry-based, propensity-matched cohort study included all patients who had primary Roux-en-Y gastric bypass or sleeve gastrectomy in Sweden from January 2007 to June 2020 who had an inflammatory bowel disease diagnosis and matched control patients without an inflammatory bowel disease diagnosis. The study included data from the Scandinavian Obesity Surgery Registry, the National Patient Register, the Swedish Prescribed Drugs Register, the Total Population Register, and the Education Register from Statistics Sweden.Results: In total, 71,093 patients who underwent bariatric surgery, including 194 with Crohns disease and 306 with ulcerative colitis, were 1:5 matched to non-inflammatory bowel disease control patients. The patients with Crohns disease had a higher readmission rate within 30 days (10.7% vs 6.1%, odds ratio = 1.84, 95% confidence interval 1.02-3.31) than the control patients, with no significant difference between the surgical methods. The patients with ulcerative colitis had a higher risk for serious post-operative complications after Roux-en-Y gastric bypass (8.0% vs 3.7%, odds ratio = 2.64, 95% confidence interval 1.15-6.05) but not after sleeve gastrectomy compared to control patients (0.8% vs 2.3%). No difference was observed in postoperative weight loss or postoperative health-related quality of life.Conclusion: Sleeve gastrectomy appears to be a safe and effective treatment for obesity in patients with inflammatory bowel disease, whereas Roux-en-Y gastric bypass was associated with a higher risk for postoperative complications in patients with ulcerative colitis.& COPY; 2023 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).