An internal hernia is the protrusion of a viscus through a normal or abnormal opening within the confines of the abdominal cavity. Internal hernias account for 0.2 to 0.9 per cent of all cases of intestinal obstruction. Paraduodenal hernias are relatively rare congenital malformations and account for 30 to 53 per cent of all internal hernias. They result from incomplete rotation of the midgut, with part of the small intestine trapped posterior to the mesocolon. Right and left paraduodenal hernias are distinct and separate entities, varying not only in anatomic structure but also in embryological origin. Symptoms are often vague, and a high index of suspicion is required to make the diagnosis. This entity should be considered whenever atypical abdominal symptoms are present. A CT scan or barium upper gastrointestinal radiography provides the best preoperative evidence of this condition, although ultrasonography and plain films are also useful. Elective repair of such a hernia should always be performed to avoid bowel incarceration or strangulation. An understanding of the anatomy of these hernias facilitates the surgery and is necessary in decreasing the likelihood of complications. Careful reduction of the hernia and surgical repair will avoid injury to the major mesenteric vessels juxtaposed to the hernial orifice. The surgical management of three patients, who were diagnosed preoperatively with this condition, is described with a review of its pathogenesis and present surgical treatment.