Most codes and declarations pertaining to the ethics of research involving human subjects have been formulated in response to specific events mostly of a painful or embarrasing nature. Several concepts appearing repeatedly in their texts are highlighted in this paper: principles of respect for persons, beneficence and justice, vulnerability and research propriety. Along with some comments on current revisions of many international guidelines and the role of bioethics committees, a plea is made to have a proactive rather than a reactive stance in ethical regulation of biomedical research (Rev Méd Chile 2001; 129: 680-4