In 1887, Dr. Andrieu of Paris read a paper before the section on dental and oral surgery of the Ninth International Medical Congress, advocating the extraction of the first permanent molars. His argument was based on the fact that 75 per cent, of these teeth decay. Black and others who have collected statistics on this subject have agreed that caries occurs in these teeth in a much larger percentage than in any other tooth in the denture, and that more of them are lost from decay than any other tooth. Since the reading of Andrieu's paper, there have been constantly appearing articles advocating the wholesale removal of these teeth. In recent years, and even at the present time, this procedure has often been advocated for avoiding, or correcting, crowding and irregularity of the teeth. The purpose of this paper is to point out the fundamental fallacy in this procedure. It