Abstract： Objective To evaluate the value of bedside index for severity in acute pancreatitis (BISAP) in predicting the severity and prognosis of acute pancreatitis (AP) by comparison with traditional scoring systems.Methods Four hundred ninety-seven patients of AP admitted into Wuxi People's Hospital from January 2005 to December 2010 were studied retrospectively.BISAP,APACHE Ⅱ,Ranson and Balthazar CT (CTSI) scores were calculated,respectively,in order to evaluate the severity.The AUC of ROC was used to evaluate the ability of BISAP and the other scoring systems in predicting the severity of AP and the occurrence of pancreatic necrosis,organ failure and mortality.Results Among 497 patients,mild acute pancreatitis (MAP) was identified in 396 patients and severe acute pancreatitis (SAP) in 101 patients.The gender,age and etiological factors between MAP and SAP were not statistical different.The BISAP,APACHE Ⅱ,Ranson scores of the 4 9 7 patients were 1.08 ± 1.01,5.79 ± 4.00,1.69 ± 1.59,and the scores were intercorrelated(r =0.612,0.568,0.577,P ＜0.001).In addition,the BISAP,APACHE Ⅱ,Ranson scores of SAP patients were significantly higher than those in MAP patients.The AUC of BISAP for SAP was 0.762(95％ CI 0.722 ～0.799),when the cutoff value was 2,the sensitivity,specificity,positive predictive value (PPV),negative predictive value ( NPV ) were 63.39％,83.08％,48.1％,89.4％ ; the AUC of BISAP for pancreatic necrosis was 0.711 (95％ CI 0.612 ～ 0.797),when the cutoff value was 2,the sensitivity,specificity,PPV,NPV were 84.6％,46.7％,35.5％,89.7％ ; the AUC of BISAP for organ failure was 0.777( 95％ CI0.683 ～ 0.854),when the cutoff value was 2,the sensitivity,specificity,PPV,NPV were 93.1％,51.4％,43.5％,94.9％ ; the AUC of BISAP for mortality was 0.808(95％ CI 0.718 ～0.880),when the cutoff value was 3,the sensitivity,specificity,PPV,NPV were 83.3％,67.4％,25.6％,96.8％.In the cases of SAP,the ability of BISAP and the other scoring systems in predicting the prognosis showed no statistical difference.Conclusions The BISAP has the prediction ability for AP severity and prognosis similar to other scoring systems,and it consists of only 5 parameters and can be completed in the fast 24 h of admission,therefore it can be used for early predication of SAP,which is worth of clinical application.