Background: Selective biliary cannulation is often difficult when there is a periampullary diverticulum, especially when the papilla is within the diverticulum. We report eight such cases in which a new technique was used to achieve biliary access. Methods: Among 4138 ERCPs, there were 246 cases (5.9%) with periampullary diverticula. Biliary cannulation initially failed in eight patients (3.3%), five of whom had previously undergone six failed attempts at other institutions. A technique was used whereby the papilla was kept out of the diverticulum by placement of a pancreatic duct stent. Needle-knife sphincterotomy was then performed followed by attempts to achieve biliary access. Results: Biliary entry was immediately successful in five patients and successful at a second ERCP in two (overall success 87.5%). Two patients developed post-ERCP pancreatitis. Conclusions: When the papilla is within the periampullary diverticulum, placement of a main pancreatic duct stent keeps the papilla out of the diverticulum, thereby facilitating pre-cut needle-knife sphincterotomy and selective biliary cannulation.