This report responds to the second referral to the Parliamentary Office for Scientific and Technological Assessment (OPECST) laid down by Article 26 of the Act of 6 August 2004 on bioethics. That Act lays down that 6 months before the end of the 5 year moratorium on the ban on embryo and embryonic stem cell research which it decrees, in other words February 2011, 'the Biomedicine Agency and the OPECST shall each draw up a report assessing the respective results of the research on embryonic stem cells and adult stem cells so as to allow a new consideration of these provisions by Parliament.' This report follows on from those presented, in the OPECST framework, on bioethics Acts, and more especially that of December 2008 on the assessment of the afore-mentioned Act, and it also comes after the many OPECST studies on bioethics. It takes into account the debates held in various fora, the opinions of the Académies, the report of the State Council and that of the National Assembly Fact-Finding Mission, and the assignments, visits and hearings undertaken by the rapporteurs in France and abroad.