Background: It remains unknown whether routine division of the greater omentum during laparoscopic Roux-en-Y gastric bypass (LRYGB) influences the risk for small bowel obstruction (SBO) afObjective: To evaluate the effect of omental division on SBO after LRYGB stratified by handling of the mesenteric defects.Setting: Nationwide, registry-based.Methods: In this registry-based cohort study, 40,517 patients who underwent LRYGB in Sweden within the period from January 1, 2007, to December 31, 2019, with data from the Scandinavian Obesity Surgery Registry (SOReg) were included. The study was based on combined data from the SOReg, the National Patient Register, the Swedish Prescribed Drugs Register, and the Total Population Registry. The main outcome was reoperation for SBO.Results: During a follow-up period of 5.9 +/- 2.6 years, the cumulative incidence of SBO was 11.2% in the nondivision group compared with 9.7% among patients with divided omentum (hazard ratio [HR] = .83, 95% confidence interval [CI]: .77-.89, P < .001). The association was seen in patients without mesenteric defects closure (HR = .69, 95% CI: .61-.78, P <.001) as well as patients withConclusion: Division of the greater omentum is associated with reduced risk for SBO after antecolic, antegastric LRYGB and should be considered as a complement to mesenteric defects closure to further reduce the risk for SBO after LRYGB. (Surg Obes Relat Dis 2023;19:178-186.) (c) 2023 American Society for Metabolic and Bariatric Surgery. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).