Migration of a biliary self-expanding metallic stent (SEMS) may occur proximally or distally after placing a stent for the palliative treatment of patients with unresectable periampullary malignancy. However, migration of a biliary SEMS into the stomach has not yet reported in the English medical literature. Herein we report on a case of periampullary cancer for which a stent that was placed to treat this malady migrated into the stomach. A biliary SEMS had been placed in the distal common bile duct in an 82-year-old woman who was diagnosed with periampullary cancer. The abdominal CT and esophagogastroduodenoscopic findings disclosed that the biliary SEMS had migrated into the stomach and there was marked luminal narrowing of the second portion of the duodenum due to the enlarged periampullary tumor. The migrated stent was easily removed by using a polypectomy snare. We presume that the distally migrated SEMS might have moved into the stomach against the normal direction of peristaltic movement instead of migrating to the intestine because of the duodenal obstruction caused by the growing mass. (Korean J Gastrointest Endosc 2008;36:324-328)