This paper describes a number of historical breaches of research ethics. Typically the victims of such breaches belong to vulnerable populations, such as prisoners, mentally disabled people, women and people in developing countries. This article provides a brief introduction to the main ethical approaches in bioethics. Subsequently it looks at a number of currently discussed ethical issues in clinical research ethics, notably the ethics standards of clinical trials in developing countries, the use of prisoners and incompetent people in clinical research, and the modus operandi of research ethics committees.