Pancreas divisum occurs when the embryological ventral and dorsal parts of the pancreas fail to fuse, so that pancreatic drainage is mainly through the accessory papilla. In 169 patients with primary biliary tract disease who underwent pancreatography incidental to endoscopic cholangiography, the incidence of pancreas divisum was 3.6%. Among 78 patients with unexplained recurrent pancreatitis, the incidence was 25.6%. The hypothesis that the duct anomaly can cause obstructive pain and pancreatitis is presented, and supported by a detailed analysis of 47 patients with the condition.