Background: Appendix invagination is a rare cause of right lower quadrant abdominal pain. Clinical findings are not specific and can mimic a wide range of diseases. Case Report: An 8-year-old girl was admitted with abdominal pain lasting for 2 weeks. Clinical and radiologic findings suggested ileocecal intussusception initially. A failed hydrostatic reduction attempt and subsequent abdominal ultrasound and computed tomography studies showed that the underlying pathology was invagination of the vermiform appendix. The patient was managed conservatively and spontaneous reduction was observed during follow-up. She underwent appendectomy 9 months later due to chronic appendicitis. Why Should An Emergency Physician Be Aware of This?: Appendix invagination should be kept in mind while evaluating patients with suspected ileocecal intussusception. In distinguishing between these two conditions, a blind-ending invaginating segment is an important clue in favor of appendix intussusception. (C) 2016 Elsevier Inc. All rights reserved.