International Workshop organised by the Marcel Mérieux Foundation, 21 to 23 June 2000. The debate over the ethical issues raised by stem cell research concerns essentially the practice of taking cells from human embryos and the consequent destruction of the embryo. This work, going to the heart of the controversy over such manipulations, discusses the ethical question of the legal status of the embryo. At the moment when, in France, the bioethics laws have come up for review, questions regarding the statute of the embryo return in the heart of scientific debates. Breakthroughs in the field of embryonic stem cell biology offer a glimpse of the considerable therapeutic possibilities. Research Institutes and Governments, hailed by these new therapeutic perspectives, are attempting to put in place modes of regulation this research that both respond to citizen's aspirations and conform to ethical norms.