Endometriosis is a common condition affecting the female genital tract, but involvement of the ileum is very rare. Its symptoms are vague and are similar to other benign and malignant disorders, and radiographic findings lack specificity. We report the case of a 23-year-old woman presenting with acute intestinal obstruction for whom preoperative diagnosis favoured acute appendicitis. Laparotomy revealed ileal stenosis. A partial small bowel resection was performed. Pathological examination diagnosed ileal endometriosis. Endometriosis may be a cause acute abdominal pain in women, and should be considered in differential diagnosis. Difficulties in establishing its diagnosis are discussed.