Objective To investigate the preventive effect of Indomethacin for post-ERCP pancreatitis and hyperamylasemia.Methods A total of 600 patients,who were undergoing ERCP,were randomly divided into 3 groups to receive anal Indomethacin (n=200),intravenous octreotide (n=200) or no special medication (n=200) before ERCP.The level of serum amylase before and 24h after ERCP were measured,and the rate of acute pancreatitis and hyperamylasemia after ERCP were assessed.Results Serum amylase levels before ERCP of all groups were normal.The mean serum amylase level of Indomethacin group (101.3±77.7 U/L) after ERCP was significantly lower than those of octreotide group ( 176.6±138.3 U/L,P =0.040 ]and control group (227.2±264.9 U/L,P=0.048),while there was no difference between octreotide group and control group ( P＞0.05 ).The incidence of post-ERCP pancreatitis in Indomethacin group (2.5％) was significantly lower than that of control group (9.5％,P=0.003),while there was no difference between octreotide group (4.5％) and control group ( P=0.05 ).The incidence of hyperamylasemia after ERCP in Indomethacin group (5.5％) was significantly lower than that of control group ( 13.5％,P=0.006 ),while there was no difference between octreotide group (10.0％) and control group ( P＞0.05 ).Conctusion Anal administration of Indomethacin before ERCP can effectively reduce the incidence of acute pancreatitis and hyperamylasemia after ERCP.