A revised diagnosis of the Pleistocene genus Procoptodon is presented. The species also are revised and diagnosed. Numerous diagnostic characters have been found in the patterns and construction of the teeth. Owen's species Procoptodon goliah (Owen), 1846, Procoptodon rapha Owen, 1873, and Procoptodon pusio Owen, 1873, are recognized. As indicated by Owen, 1874, Pachysiagon otuel is a synonym of Procoptodon pusio. All of these are from late Pleistocene faunas. No specimens of Procoptodon are now known from older faunas. It is thought that a common ancestry of Procoptodon and Sthenurus in the Sthenurinae is much farther back in the Tertiary than has been previously assumed.