Mesocolic hernia is a rare congenital anomaly caused by an error of rotation of the midgut. It may be seen as total encapsulation of the small bowel or a single loop within a hernial sac. It may be asymptomatic or cause life-threatening intestinal obstruction. Symptoms, when present, are often chronic vague abdominal pain and intermittent obstructive episodes. We have encountered a 40-year-old woman with a congenital mesocolic hernia. Abdominal CT provided the diagnosis. She successfully underwent operation and discharged with good condition. Now we present a case of congenital mesocolic hernia with a review of some articles.