Paraduodenal hernias occur uncommonly and produce symptoms only rarely. We describe a patient who developed mechanical small bowel obstruction 4 days after the excision of an acutely inflamed appendix. At laparotomy an obstructed left paraduodenal hernia was found to be the cause. No bowel resection was necessary, the hernia was reduced and the defect obliterated. The patient did very well postoperatively. A comprehensive review of the literature is also presented with particular reference to aetiology, diagnosis and the treatment of the left paraduodenal hernias.