Pluripotency defines the ability of a cell to self-renew and to differentiate into all embryonic lineages both in vitro and in vivo. This definition was first established mainly with the mouse model and the establishment of mouse embryonic stem cells (ESCs) in the 1980's and extended later on to other species including non-human primates and humans. Similarly, chicken ESCs were derived and established in vitro from pregastrulating embryos leading to cells with unique properties at molecular, epigenetic and developmental levels. By comparing the properties of murine, mammalian and avian ESCs and of the more recently discovered induced pluripotential stem (iPS)-derived cells generated in all of these species, avian specificities start to emerge including specific molecular genes, epigenetic mark profiles and original developmental properties. Here, we present common, but also avian-specific elements that contribute to defining avian pluripotency.