With the expansion of both laparoendoscopic surgery and the number of those performing it, the surgeon must remain cognizant of the uncommon complication of herniation through a previous trocar site. Herniation through laparoscopic trocar defects most often occurs as a Richter's hernia, hence its presentation can be insidious and can lead to significant morbidity. A retrospective chart review of 1300 consecutive laparoscopic cholecystectomies over 5 years was performed. An incidence of 0.77 per cent for trocar site herniations was found. All of the trocar site hernias occurred through large (> or = 10 mm) defects at the umbilical site. Ninety per cent of those patients with trocar site herniations had an umbilical hernia or midline incisional hernia found incidentally upon entrance into the peritoneal cavity. All of the herniations occurred despite primary fascial closure of the trocar sites. One trocar site hernia resulted in a small bowel obstruction secondary to an incarcerated Richter's hernia. This required a small bowel resection. Consequently, we now close trocar fascial defects in patients with preexisting hernias in a formal fashion. We recommend that trocar ports be removed under direct vision and that large fascial defects (> or = 10mm) be primarily closed. Furthermore, we recommend in those patients with incidentally found umbilical hernias that both the fascial edge and complete extent of the hernia defect be defined and then closed as a formal herniorrhaphy with interrupted nonabsorbable suture and a synthetic patch if necessary.