The current limits and rather disappointing results of gene therapy have resulted in a significant renewal of interest in cellular biology and especially for embryonic and adult stem cells. Today, stem cells, especially embryonic stem cells, are often front-page news. Indeed, they may drastically change our lives, potentially allowing for the development of new diagnostic methods and therapies for treating currently incurable diseases such as Alzheimer's and Parkinson's. However, the fulfillment of these promising prospects remains far from certain, contrary to what is often reported or implied by the media or various stands which scandalously hold out false hopes to the sick and their loved ones. In addition, the unregulated use of new techniques can constitute a threat, in particular the risk of a new form of eugenics emerging. In this report, commissioned by the National Assembly and the Parliamentary Office for the Evaluation of Scientific and Technological Choices, Alain Claeys takes precise stock of the progress made in this domain. He therefore presents an unbiased report of the real situation of this domain which is often overly praised or criticized. He also allowed the researchers to have their word, so as to inform the public of the most important and real issues in this field. A day of public hearings by the French experts in this domain was therefore held on 22 November 2005 before the National Assembly, at a time when the world's scientific community was distressed by the discovery of a scientific fraud perpetrated by a Korean team of researchers. Alain Claeys strongly hopes that this report will be the subject of serious discussions, in particular during the upcoming elections, concerning the important issues raised by embryonic stem cell research and, especially, the ethical aspects of ovocyte donations and the risk of an emerging stem cell market.