Pluripotent immortal stem cell lines have become an important new tool to study early human development and also possess great clinical potential for transplantation and tissue regeneration therapies. In this issue, Pera and colleagues have confirmed the generation of embryonic stem (ES) cells from human blastocysts and have demonstrated their subsequent differentiation into a neuronal progenitor cell in vitro. Not only do these workers verify the characteristics of human ES cells, they substantiate the differences and similarities between other types of pluripotent cells. They also demonstrate expression of Oct 3/4, which should allow parallels to be drawn with murine ES cells which have been more extensively studied to date for practical reasons (see p. 399).