Gallstone ileus is an uncommon cause of mechanical obstruction due to a biliary stone that wedges the intestinal lumen. It is a surgical emergency representing a clinical and diagnostic challenge: the clinical manifestations are rarely specific, often causing diagnostic delay that can adversely affect the prognosis. Emergency ultrasound could be useful in assessing the level and identifying the cause of bowel obstruction. We report a case of a 74-year-old patient with a 6-day history of constipation and crampy abdominal pain without previous history of abdominal diseases. Emergency ultrasound led to an early diagnosis showing dilated small bowel loops with a shadowing mass inside consistent with an ileal stone, in the absence of aberrant located stone on plain abdominal film.