EVER since they have been classified as ruminants in the Old Testament (Leviticus 11:6, Deuteronomy 14:7) and equated with hyraxes in the vulgate Latin translation, rabbits and their relatives (order Lagomorpha) have frequently experienced radical changes in taxonomic rank. By using 91 orthologous protein sequences, we have attempted to answer the classical question "What, if anything, is a rabbit?"1. Here we show that Lagomorpha is significantly more closely related to Primates and Scandentia (tree shrews) than it is to rodents. This newly determined phylogenetic position invalidates the superordinal taxon Glires (Lagomorpha + Rodentia), and indicates that the morphological 'synapomorphies' previously used to cluster rodents and lagomorphs into Glires2,3, may actually represent symplesiomorphies or homoplasies that are of no phylogenetic value. This raises the possibility that the ancestral eutherian morphotype may have possessed many rodent-like morphological characters.