OBJECTIVE: To evaluate the effectiveness and safety of a Shenlingbaizhu (SLBZ) formula in the treatment of irritable bowel syndrome (IBS). The effectiveness of SLBZ with or without conventional treatment was compared to that of conventional treatment alone. METHODS: A comprehensive literature search of four Chinese electronic databases, three English language databases, and two English language trial registries from inception to June 2019 was performed. Two authors independently screened the citations and retrieved full publications of randomized trials on the use of SLBZ with or without conventional treatment for IBS. The methodological quality of the trials was assessed with the Cochrane Collaboration's tool for assessing the risk of bias. Data were extracted and subjected to Meta-analysis to compare the efficacy of the SLBZ formula with or without conventional treatment to conventional treatment alone. RESULTS: Thirteen trials (comprising a total of 868 patients with IBS) were included in this review. The risk of bias of all 13 included trials was assessed as moderate. The SLBZ formula was associated with significant improvements in cure rate [relative risk (RR) score of 2.38, 95% confidence interval (CI) 1.43 to 3.95, I 2 = 0%; 8 trials, n = 487, fixed-effects model (FEM)], diarrhea severity score [mean difference (MD) score of －0.62, 95% CI －1.05 to －0.20, I 2 = 88%; 4 trials, n = 286, random effects model (REM)], abdominal pain severity score (MD score of －0.61, 95% CI －0.70 to －0.52, I 2 = 63%; 4 trials, n = 286, FEM), and abdominal distention severity score (MD score of －0.88, 95% CI －1.54 to －0.21, I 2 = 91%; 3 trials, n = 226, REM) compared to the conventional treatment alone. Adverse events were reported in five trials but only one of these indicated any adverse events associated with SLBZ. CONCLUSION: Based on the 13 trials reviewed here, the SLBZ formula with or without conventional treatment appeared to be safe and more effective in improving the cure rate and reducing the severity of diarrhea, abdominal pain, and abdominal distention compared to conventional treatment alone. However, these trials only generated a moderate quality of evidence, and well-designed and high-quality random controlled trials of the SLBZ formula for the treatment of IBS are required to confirm the efficacy of this treatment option.