Several antiviral restriction factors (e.g. APOBEC3G, Tetherin, and SAMHD1) have been demonstrated to evolve under positive selective pressure from viruses [21] [22] [23] [24] [25] [26] [27] [28] [29] . As important virus inhibitors, IFITM1, IFITM2 and IFITM3 may have also undergone a similar co-evolutionary process, such as other antiviral restriction factors do. Despite this connection, relationships between antiviral functions and adaptive evolution in IFITM family have seldom been reported and although previous reports had illustrated the phylogenetic history of IFITM family in some eukaryotic species [2, 30, 31] , there has been no detailed information about IFITM genes in vertebrates. In this study, we performed detailed evolutionary analyses not only to test whether the primate IFITM genes evolved under positive selection throughout primate evolution, but also to unravel the evolutionary history of vertebrate IFITM family.