BACKGROUND: Irritable bowel syndrome (IBS) is a disorder which has considerable effect to patient's quality of life and social functioning. Its main symptoms include recurrent abdominal pain and/or bloating associated with abnormal stool form or frequency. The recommendable treatment of IBS is a medication including loperamide, cimetropium, tricyclic antidepressants, and selective serotonin receptor inhibitors, but it has limited effects and several side effects dissatisfy IBS patients. As an alternative therapy, Xiaoyao-san (XYS) is gaining interest for IBS patients. XYS, a traditional Chinese medicine (TCM), has wide scope of indications and it can be prescribed for various gastrointestinal disorders in TCM syndromes but there has been no systematic review on IBS. Therefore, this review aims on systematically validating the curative effect of XYS on IBS. METHODS: Electronic databases, manual search, and contact to author e-mail will be used for searching randomized controlled trials about the use of XYS for IBS. We will select studies by the predefined criteria and collect the data on study participants, interventions, control groups, outcome measurement, adverse events, and risk of bias. Primary outcome will be the efficacy rate, and secondary outcomes will be the IBS-centered indices (abdominal pain score, abdominal distension score, diarrhea or constipation score, bowel symptom severity scale), index about quality of life, and adverse events. Review Manager software and Cochrane Collaboration "risk of bias" tools will be used for meta-analysis and assessment of risk of bias. RESULTS: This review will identify the clinical evidence of XYS's effectiveness and safety for IBS according to formal evaluation aspects. CONCLUSION: This review will further support the evidence-based usage of XYS for IBS treatment. ETHICS AND DISSEMINATION: No ethical approval is required since there is no personal information collection and patient recruitment. TRIAL REGISTRATION NUMBER: Research Registry; reviewregistry986.