An analysis of endoscopic retrograde cholangiopancreatography (ERCP) examinations suggests that repeated contrast injection into the pancreatic duct during attempts to cannulate the bile duct is of major importance in the aetiology of acute pancreatitis after ERCP, even in the absence of pancreatic acinar opacification. The technique of ERCP can easily be modified to avoid repeated pancreatic duct injection and, by doing so, an increase in the incidence of acute pancreatitis has been reversed.