Gallstone ileus is a rare disease that accounts for 1-4% of intestinal obstructions. Almost exclusively a condition in the older female population, it is a difficult diagnosis to make. We report the case of gallstone ileus in a 94-year-old Caucasian female, who presented to the emergency department with acute-onset nausea, coffee-ground emesis, lack of bowel movement, and abdominal distension. On CT scan, the diagnosis of gallstone ileus was made by the presence of a cholecystoduodenal fistula, pneumobilia, and small bowel obstruction. Emergent laparotomy with a one-stage procedure of enterolithotomy and stone removal by milking the bowel distal to the stone were performed. The postoperative course was uneventful until postoperative day 4 when the patient was found tachycardic, lethargic, and unresponsive. We reviewed the literature on the diagnosis and treatment of gallstone ileus.