These pages contain guidelines and other articles compiled by ESHRE Special Interest Groups and others, and agreed by the EHSRE Executive Committee. They are not submitted to journal peer review. In this fourth statement of the ESHRE Taskforce on Ethics and Law, the focus is on ethical issues raised by the possible therapeutic use of stem cells, and in particular from embryo stem cells. General ethical principles are discussed, including autonomy, beneficience, maleficience and freedom of research. Specific points are raised concerning the source of embryos for stem cells and of oocytes for somatic cell nuclear transfer.