The stools of 45 patients with proven gallstones pancreatitis were screened for gallstones. An equal number of peripheral with gallstones but without pancreatitis served as the control group. Gallstones were found in the stools of 38 of the 45 patients (84 percent) with gallstone pancreatitis and in only five (11 percent) patients of the control group. The patients with gallstone pancreatitis experienced a relief of symptoms and a decrease in the levels of serum amylase and bilirubin prior to rectal passage of the stones. Operative cholangiography revealed reflux of contrast material into the pancreatic duct of 67 percent of the patients with gallstone pancreatitis and in only 18 percent of the controls. Of the 38 patients that passed stones, 30 cholangiograms (79 percent) demonstrated a functioning common channel. it would appear that a functioning common channel is necessary for reflux and in addition favors stone passage. This study suggests that the pathophysiology of gallstone pancreatitis relates to the temporary impaction of migrating stones at the ampulla of Vater.