The Parliamentary Office for the Evaluation of Scientific and Technological Choices organised a public session to address the potential risks and ethical stakes of nanotechnologies. The purpose of the meeting, chaired by Mr. Claude Birraux, Deputy, Senior Vice-Chairman of the Office, and Mr. Daniel Raoul, Senator, was to ensure that the Office’s reports on this subject were followed up and also to provide information for the many current debates on nanotechnologies and develop this information in-depth. This day session open to the press, which was attended by chairmen of ethical commissions and committees, directors of research in physics, chemistry and medicine, economists, industrialists and representatives of associations, was held on 7 November 2006 in the National Assembly. Focusing on the risks and the ethical questions raised by the use of nanotechnologies and the responses that all the various persons involved are trying to contribute, the hearing led to a comprehensive review of the specificities of nanotechnologies, the considerable industrial stakes they represent and the progress that could be made with them in the areas of health care, the environment, transport and security. However, the discussions also revealed that no studies have been made higher up the chain about the ethical stakes, the uncertainties of the danger to mankind and his environment, particularly because measuring instruments have not been perfected so far, and the difficulties of applying the principle of precaution with discernment to these technologies. Various opinions were also expressed on the impact of innovations relying on converging NBIC technologies and the control of the speed of scientific progress.