Objectives: Ileus commonly occurs after abdominal surgery, and is associated with increased length of hospital stay (LOHS). We ex- plored whether postoperative chewing gum (CG) reduces ileus by accelerating return of gastrointestinal (GI) function. Methods: We searched six electronic databases and hand-searched for randomised-controlled trials (RCTs) on the use of postoperative CG in abdominal surgery patients. We split studies into colorectal surgery, caesarean section and other surgery subgroups. We assessed risk of bias (ROB) using an adapted Cochrane ROB tool. We assessed effects of CG on time to first flatus (TFF), time to bowel movement (TBM) and LOHS via random-effects model meta-analyses. We also considered the effect of CG on complications and conducted a sen- sitivity analysis in studies within an Enhanced Recovery After Surgery (ERAS) context. Results: We found 81 eligible studies that recruited 9072 participants to include in our review. Many studies were at high or unclear ROB. There was statistical evidence that compared to controls, use of CG reduced TFF overall by 10.4 hours (95% CI: -11.9, -8.9), TBM by 12.7 hours (95% CI: -14.5, -10.9) and LOHS by 0.7 days (95% CI: -0.8, -0.5). There was statistical evidence of heterogeneity in all analyses, and visual inspection of the funnel plots indicated that re- porting bias may be present for TBM and LOHS. Effect sizes were greatest in the colorectal surgery subgroup and smallest in the cae- sarean section subgroup. There was little difference between treatment groups in mortality, infection and readmissions. The ERAS sensitivity analysis (four studies) showed that compared to controls, use of CG reduced TFF by 6.2 hours (95% CI: -15.4, 3.0) and TBM by 21.1 hours (95% CI: -33.1, -9.2), but did not affect LOHS (in- crease of 0.1 days, 95% CI: -0.4, 0.5). Conclusion: We found some evidence for a benefit of postoperative CG on GI function recovery, although many trials were small and of poor quality. Many components of ERAS reduce risk of ileus, which may explain the apparent reduction in effectiveness of CG alongside ERAS programmes. Well-designed adequately-powered RCTs are needed to demonstrate the effectiveness of CG after surgery in contemporary populations in ERAS settings. Disclosure of Interest: None Declared.