Postoperative ileus (POI) is a common complication following colorectal surgery that delays recovery and increases length of hospital stay. Gum chewing may reduce POI and therefore enhance recovery after surgery. The aim of the study was to evaluate the effect of gum chewing on POI, length of hospital stay and inflammatory parameters. METHODS: Patients undergoing elective colorectal surgery in one of two centres were randomized to either chewing gum or a dermal patch (control). Chewing gum was started before surgery and stopped when oral intake was resumed. Primary endpoints were POI and length of stay. Secondary endpoints were systemic and local inflammation, and surgical complications. Gastric emptying was measured by ultrasonography. Soluble tumour necrosis factor receptor 1 (TNFRSF1A) and interleukin (IL) 8 levels were measured by enzyme-linked immunosorbent assay. RESULTS: Between May 2009 and September 2012, 120 patients were randomized to chewing gum (58) or dermal patch (control group; 62). Mean(s.d.) length of hospital stay was shorter in the chewing gum group than in controls, but this difference was not significant: 9.5(4.9) versus 14.0(14.5) days respectively. Some 14 (27 per cent) of 52 analysed patients allocated to chewing gum developed POI compared with 29 (48 per cent) of 60 patients in the control group (P = 0.020). More patients in the chewing gum group first defaecated within 4 days of surgery (85 versus 57 per cent; P = 0.006) and passed first flatus within 48 h (65 versus 50 per cent; P = 0.044). The decrease in antral area measured by ultrasonography following a standard meal was significantly greater among patients who chewed gum: median 25 (range -36 to 54) per cent compared with 10 (range -152 to 54) per cent in controls (P = 0.004). Levels of IL-8 (133 versus 288 pg/ml; P = 0.045) and TNFRSF1A (0.74 versus 0.92 ng/ml; P = 0.043) were lower among patients in the chewing gum group. Fewer patients in this group developed a grade IIIb complication (2 of 58 versus 10 of 62; P = 0.031). CONCLUSION: Gum chewing is a safe and simple treatment to reduce POI, and is associated with a reduction in systemic inflammatory markers and complications. Registration number: NTR2867 ( http://www.trialregister.nl).