Abstract:Objective：To explore whether low molecular weight heparin (LMWH) could prevent acute pancreatitis after ERCP and its clinical significance. Methods：Sixty patients were randomly divided into 2 groups(30 in each group): ERCP group (E group), LMWH prevention group (H group). Changes of abdominal pain, biochemical parameters of amylase(AMS), endotoxin(ET),interleukin-6(IL6),nitricogen oxide(NO) and pancreatic morphology under ultrasonography between the two groups were investigated. Changes of coagulation function in H group before and after ERCP were also studied. Results：Abdominal pain of 5 patients in E group(16.7%) was aggravated, but none of H group. There were no significant differences in the values of biochemical parameters and pancreatic morphology between the two groups before ERCP. The values of AMS,ET in E group were significantly higher at 4h and 24h after ERCP than those of H group（P<0.05）; meanwhile the values of NO in H group were significantly higher at 4h and 24h than those of E group（P<0.05）. The values of IL6 in E group were significantly higher after ERCP than those of H group at all time points (P<0.05). One patient in E group had acute inflammatory change of pancreas under ultrasonography. No obvious change of coagulation function was observed after ERCP in H group（P>0.05）. Conclusions：LMWH therapy may prevent or reduce the occurrence of acute pancreatitis in those who undergo ERCP by improving microcirculation and reducing the release of inflammatory mediators, and is a simple, economic and safe method .