AIM: To assess the clinical outcomes of pre-, pro-and synbiotics therapy in patients with acute pancreatitis. METHODS: The databases including Medline, Embase, the Cochrane Library, Web of Science and Chinese Biomedicine Database were searched for all relevant randomized controlled trials that studied the effects of pre-, pro- or synbiotics in patients with acute pancreatitis. Main outcome measures were postoperative infections, pancreatic infections, multiple organ failure (MOF), systemic inflammatory response syndrome (SIRS), length of hospital stay, antibiotic therapy and mortality. RESULTS: Seven randomized studies with 559 acute pancreatic patients were included. Pre-, pro-or synbiot-ics treatment showed no influence on the incidence of postoperative infections [odds ratios (OR) 0.30, 95% conf idence interval (CI): 0.09-1.02, P = 0.05], pancre- atic infection (OR 0.50, 95% CI: 0.12-2.17, P = 0.36), MOF (OR 0.88, 95% CI: 0.35-2.21, P = 0.79) and SIRS (OR 0.78, 95% CI: 0.20-2.98, P = 0.71). There were also no signif icant differences in the length of antibiotic therapy (OR 0.75, 95% CI: 0.50-1.14, P = 0.18) and the mortality (OR 0.75, 95% CI: 0.25-2.24, P = 0.61). However, Pre-, pro-or synbiotics treatment was associ- ated with a reduced length of hospital stay (OR -3.87, 95% CI: -6.20 to -1.54, P = 0.001). When stratifying for the severity of acute pancreatitis, the main results were similar. CONCLUSION: Pre-, pro-or synbiotics treatment shows no significant influence on patients with acute pancreatitis. There is a lack of evidence to support the use of probiotics/synbiotics in this area. METHODS: The databases including Medline, Embase, the Cochrane Library, Web of Science and Chinese Biomedicine Database were searched for all relevant randomized controlled trials that studied the effects of pre-, pro- or synbiotics in patients with acute pancreatitis. Main outcome measures were postoperative infections, pancreatic infections, multiple organ failure (MOF), systemic inflammatory response syndrome (SIRS), length of hospital stay, antibiotic therapy Pre-, pro-or synbiot-ics treatment showed no influence on the incidence of postoperative infections [odds ratios (OR) 0.30, 95% conf idence interval (CI (OR 0.88, 95% CI: 0.35-2.21, P = 0.79) and SIRS (OR 0.78, 95% CI: 0.20-2.98, P = 0.71). There were also no sign of icant differences in the length of antibiotic therapy (OR 0.75, 95% CI: 0.50-1.14, P = 0.18) and the mortality (OR 0.75, 95% CI: 0.25-2.24, P = 0.61). However, Pre-, pro- or synbiotics treatment was associated with a reduced length of hospital stay (OR -3.87, 95% CI: -6.20 to -1.54, P = 0.001). When stratifying for the severity of There are a lack of evidence to support the use of probiotics / synbiotics in this area.