Internal hernia may be either congenital or acquired. Its incidence has been reported to be 1–2%. Internal hernia is a rare cause of small bowel obstruction with a reported incidence of 0.2–0.9%. The herniation may lead to a variable degree of vascular compromise to the herniated bowel. We report a rare case of spontaneous transmesenteric hernia of ileum with associated gangrene of bowel caused by a congenital mesenteric defect in a 35-year-old adult male, and review the relevant literature.