A case of an incarcerated Richter's hernia in a 12-mm trocar site is presented. A 72 year old man underwent laparoscopic herniorrhapy because of a recurrent inguinal hernia. On the sixth postoperative day he developed abdominal pain, nausea, vomiting and abdominal distension. Plain abdominal X-ray showed bowel obstruction. Computed tomography with oral contrast showed herniation of small bowel above the fascia. The patient was immediately reoperated, the intestine was reduced, and the fascial defect at the trocar site closed. Three days later he underwent surgery again due to a small perforation of the small bowel and a persistent fascial defect. The patient had an uneventful postoperative course. Herniation through a trocar site is a rare complication-incarceration extremely rare. We recommend that all fascial defects of 10 mm or more are closed sufficiently.