Objective: To evaluate the effect and safety of acupuncture for the treatment of irritable bowel syndrome (IBS) through comparisons with those of polyethylene glycol (PEG) 4000 and pinaverium bromide. Patients and Methods: This multicenter randomized controlled trial was conducted at 7 hospitals in China and enrolled participants who met the Rome III diagnostic criteria for IBS between May 3, 2015, and June 29, 2018. Participants were first stratified into constipation-predominant or diarrheapredominant IBS group. Participants in each group were randomly assigned in a 2:1 ratio to receive acupuncture (18 sessions) or PEG 4000 (20 g/d, for IBS-C)/pinaverium bromide (150 mg/d, for IBS-D) over a 6-week period, followed by a 12-week follow-up. The primary outcome was change in total IBS-Symptom Severity Score from baseline to week 6. Results: Of 531 patients with IBS who were randomized, 519 (344 in the acupuncture group and 175 in the PEG 4000/ pinaverium bromide group) were included in the full analysis set. From baseline to 6 weeks, the total IBS-Symptom Severity Score decreased by 123.51 (95% CI, 116.61 to 130.42) in the acupuncture group and 94.73 (95% CI, 85.03 to 104.43) in the PEG 4000/pinaverium bromide group. The between-group difference was 28.78 (95% CI, 16.84 to 40.72; P<.001). No participant experienced severe adverse effects. Conclusion: Acupuncture may be more effective than PEG 4000 or pinaverium bromide for the treatment of IBS, with effects lasting up to 12 weeks.