Background: Secretin, a 27 amino acid polypeptide released in response to duodenal luminal acidification, stimulates secretion of water and bicarbonate from pancreatic ductal cells. To date the only secretin available for clinical use has been a biologically derived compound extracted from porcine duodenums. Although used to facilitate pancreatic duct cannulation, secretin has not been approved for this indication. In this study, a new synthetic porcine secretin with an identical amino acid composition was compared with saline solution for the facilitation of minor papilla cannulation in patients with pancreas divisum. Methods: A multicenter, prospective, randomized, placebo-controlled, double-blind, comparative trial was conducted at 4 centers with expertise in pancreaticobiliary endoscopy. Patients with pancreas divisum in whom minor papilla cannulation initially was unsuccessful were enrolled. Either saline solution (placebo) or synthetic porcine secretin was administered. If the minor papilla orifice and/or pancreatic juice flow was noted, cannulation was attempted and success or failure was documented (phase 1), as well as the time taken for successful cannulation. If cannulation was unsuccessful, no juice flow was noted, or the orifice was not seen, the alternate agent was administered (phase 2). Results: Twenty-nine patients (7 men, 22 women; mean age 51 years, range 21-76 years) were enrolled. In phase 1, cannulation was achieved in 1 of 13 patients (7.7%) after the placebo was given and in 13 of 16 patients (81.3%) after synthetic porcine secretin was given (p < 0.0001). In phase 2, cannulation was achieved in 12 of 12 patients (100%) after synthetic porcine secretin was given and in 0 of 3 patients (0%) after the placebo was given (p = 0.0022). Overall, cannulation was successful in 25 of 28 patients (89.3%) who received synthetic porcine secretin and in 1 of 16 (6.3%) who received the placebo (p < 0.0001). Mean time to cannulation was significantly greater for the placebo than for the synthetic porcine secretin (4.75 min vs. 2.63 min; p = 0.0001). No adverse events directly attributable to synthetic porcine secretin administration were documented. Conclusions: This study confirmed the use and safety of synthetic porcine secretin in facilitating cannulation of the minor papilla in patients with pancreas divisum in whom cannulation was difficult. Use of this agent has the potential to further increase the cannulation success rate in this group of patients. (Gastrointest Endosc 2003;57:643-7.)