A 9 month old male presented with an acute abdomen and was found to have free air on abdominal radiographs and CT. The source of the free air was unable to be found on imaging, but a possibility that it may have originated from a blind-ended fluid structure in the pelvis. This structure was thought to be an abnormal appendix or Meckel's diverticulum, although a ruptured appendix typically does not cause a significant amount of pneumoperitoneum, it remains a differential diagnosis. Laparotomy was performed and a perforated Meckel's diverticulum was identified.