A prospective study of choledocholithiasis was performed using 110 patients with presumptive diagnoses of acute gallstone pancreatitis. The incidence of migrating and persistent bile duct stones was determined using stool screening and intraoperative cholangiography, and the clinical significance of continued stone obstruction of the papilla was investigated using ultrasound assessment of migration time and a second evaluation of prognostic signs. Pancreatic inflammation was confirmed at surgery in 51 patients, of whom only 27 had stones in the stools (n = 22) or the bile duct (n = 5), suggesting that choledocholithiasis may not be the sole triggering factor of acute gallstone pancreatitis. Neither delayed migration nor persistent stone obstruction of the papilla promoted pancreatic inflammation.