Gallstone ileus in association with Crohn's disease of the terminal ileum is a surprisingly uncommon occurrence. The diseased ileal segment may be responsible for gallstone lithogenesis as well as for luminal stenosis that prevents gallstone passage. We report only the third case of gallstone ileus in Crohn's disease and the first to be correctly diagnosed before surgery. The patient was successfully managed by planned ileal resection and cholecystectomy.