Alimentary tract duplication is a rare congenital anomaly which may involve any part of the alimentary tract extending from stomach to rectum. Clinical presentation may mimic an inflamed appendix as described in this case. A 9-year-old boy with a clinical diagnosis of perforated appendix was noted to have a normal appendix intra-operatively. On further search for an underlying pathology, a gangrenous ileal duplication was discovered. En-bloc resection with primary bowel anastomosis was done. Histopathology report revealed a gangrenous small bowel duplication. We discuss the preoperative diagnostic dilemma and management options in approaching this rare entity. © 2017, Malaysian Medical Association. All rights reserved.