A prospective randomised study was designed to evaluate the efficacy of protecting the lingual nerve by subperiosteal insertion of a retractor in 300 patients. All operations were performed under local anaesthesia and only one molar was removed at a time. In one group, the lower third molar was removed with protection of the lingual nerve and in another group, without protection. Molars which did not need to be sectioned were excluded from the study. The position of the molar, the degree of surgical difficulty and patient gender and age were also recorded. The results indicate 1.33% incidence of temporary lingual nerve dysaesthesia--this being low in comparison with other studies. No permanent disturbances were found. The intergroup percentage difference was not significant. It is suggested that routine application of a lingual protecting instrument during surgical removal of a third molar is not necessary in the hands of an experienced surgeon.