This is a case report of a 70-year-old woman with possible cholestyramine-induced bowel perforation. She had a prior history of pancreaticoduodenectomy for pancreatic cancer with a daily intake of cholestyramine. She underwent emergency laparotomy for small bowel perforation twice. Subsequent pathology reports showed crystal depositions in the small bowel wall. Leasions spread out on the small bowel and the omentum during the second surgery were thought to be carcinomatosis. However, the pathology report showed no malignant cells but plenty of crystal depositions as seen with cholestyramine intake.