A survey was carried out on 60 patients for whom lower second molar removal had been recommended at least 5 years previously, no other treatment being indicated in the lower arch. Of the 114 teeth recommended for removal, only 84 were extracted. Eighty four per cent of third molars erupted satisfactorily, where second molars had been extracted, while only 36 per cent of third molars erupted into good occlusion where the recommended extractions had not been carried out. In the extraction group, factors associated with a poor result were lack of third molar root formation at the time of removal of the second molar and space between the third molar crypt and the lamina dura of the second molar.