Duodenal perforation may occur at the time of insertion of a biliary endoprosthesis or following endoscopic manipulation of such a stent. The possibility of perforation as a late sequela of stent migration, after percutaneous placement of an endoprosthesis, however, has not been emphasized. In the authors' experience with a 12-F soft-stent endoprosthesis, duodenal perforation occurred in four of 50 patients following initially satisfactory stent placement. One intraperitoneal perforation necessitated immediate surgical intervention. The three retroperitoneal perforations were treated conservatively.