The Bedside Index for Severity in Acute Pancreatitis (BISAP) score has been developed to identify patients at high risk for mortality or severe disease early during the course of acute pancreatitis. We aimed to undertake a meta-analysis to quantify the accuracy of BISAP score for predicting mortality and severe acute pancreatitis (SAP). We searched the databases of Pubmed, Embase, and the Cochrane Library to identify studies using the BISAP score to predict mortality or SAP. The pooled sensitivity, specificity, likelihood ratios, and diagnostic odds ratio (DOR) were calculated from each study and were compared with the traditional scoring systems. Twelve cohorts from 10 studies were included. The overall sensitivity of a BISAP score of ≥3 for mortality was 56% (95% CI, 53%-60%), with a specificity of 91% (95% CI, 90%-91%). The positive and negative likelihood ratios were 5.65 (95% CI, 4.23-7.55) and 0.48 (95% CI, 0.41-0.56), respectively. Regarding the outcome of SAP, the pooled sensitivity was 51% (43%-60%), and the specificity was 91% (89%-92%). The pooled positive and negative likelihood ratios were 7.23 (4.21-12.42) and 0.56 (0.44-0.71), respectively. Compared with BISAP score, the Ranson criteria and APACHEⅡscore showed higher sensitivity and lower specificity for both outcomes. The BISAP score was a reliable tool to identify AP patients at high risk for unfavorable outcomes. Compared with the Ranson criteria and APACHEⅡscore, BISAP score outperformed in specificity, but having a suboptimal sensitivity for mortality as well as SAP.