Acute pancreatitis is a serious complication of endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic sphincterectomy (EST). In addition, serum pancreatic enzymes increase without clinical symptoms in up to 75% of patients undergoing endoscopic procedures. The aim of this trial was to investigate the effects of octreotide in the prevention of these possible complications in patients undergoing therapeutic ERCP. The study was carried out in 209 subjects who were randomly allocated to two groups (A and B). Group A received 0.5 mg of octreotide-acetate subcutaneously one hour prior to ERCP; group B was given placebo. Serum amylase and lipase values were measured before premedication and 1.5, 2, 6 and 24 hours following endoscopy. Following ERCP, the increase in both amylase and lipase values was significantly greater in the control (placebo) group, but this significance disappeared 24 hours following the procedure. Symptoms of acute pancreatitis developed in 4 (3.85%) patients who were given octreotide-acetate, compared to 10 (9.52%) patients in the control group. The results obtained in our study seem to indicate that octreotide could prevent the increase in serum pancreatic enzymes, but no significant difference was observed in the prevention of post-ERCP pancreatitis.