Background and Study Aim:In several studies non-steroidal anti inflammatory drugs (NSAIDs) showed reduction of post (ERCP) pancreatitis incidence and severity. Our aim is to study the effect of NSAIDs in reducing post ERCP pancreatitis (PEP). Patients and Methods: A double blind placebo controlled study was conducted, patients who underwent ERCP in Specialized Arab Hospital (SAH), collected over one year, from June 2012 to June 2013 . Patients were randomized by an endoscopy nurse to receive IM Diclofenac 75 mg, or IM isotonic saline 3 ml as placebo. 12 hours after completing the procedure all patients were evaluated for abdominal pain and serum amylase. Results: The total number of patients was 199 patients, 17 patients were excluded, 182 patients completed the study, diclofenac group (89), placebo (93), the two groups were comparable for the following: age, sex, ERCP finding, pancreatic duct cannulation, failure of common bile duct (CBD) cannulation, number of pancreatic duct cannulation, ERCP time, sphincterotomy, and stenting. The overall incidence of pancreatitis was (18/182) 10%, (6/89) 6.9% for the diclofenac group and (12/93) 12.9% for the placebo group. There was no significant difference in the incidence of pancreatitis between the two groups; the P value was 0.164. In all the cases in which pancreatitis occurs, it was mild or moderate; there was no severe pancreatitis among the two groups. But in subgroup analysis the frequency of pancreatitis in patients with multiple pancreatic duct cannulation was significantly lower in the diclofenac group than in control group with p value = 0.021. Conclusion: Intramuscular diclofenac does not lower PEP rate or severity. But it significantly decreased PEP in patients with multiple pancreatic duct cannulations.