This study was designed to evaluate the effect of aggressive Hydration versus NSAID (nonsteroidal anti-inflammatory drug) therapy in prevention of post ERCP (Endoscopic Retrograde Cholangiopancreatogram) pancreatitis. A double blind randomized controlled clinical trial study including 186 patients will conducted on three groups of hospitalized patients (n=62) undergoing ERCP procedure in gastrointesitinal ward at Imam Khomeini Hospital, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Patients and evaluating physician are blinded regarding type of intervention. Patients will randomly assigned to the group of study using random list. Inclusion criterion is ERCP for biliary stones or stenting insertion. Exclusion criteria are acute cholangitis, Sepsis, chronic pancreatitis, acute pancreatitis caused by gallstones, patients undergoing balloon dilatation of papilla, patients at risk due to increased fluid volume, heart diseases, pregnant women, history of pancreatitis after ERCP, patients who had pancreatic stent. The first group will receive the solution ringer lactate bolus 20 cc/kg then 3 cc/kg/h after ERCP procedure (n=62) and the second group will receive one indomethacin rectally every 12 hours for 24 hours (n=62) and the third group will receive placebo (n=62) after ERCP. To confirm the diagnosis of pancreatitis, every 8 and 24 hours after intervention the abdominal pain and amylase level will be assessed. In the case of abdominal pain and amylase level over 270 IU/dl the pancreatitis will be confirmed.