Increasing numbers of people are seeking genetic testing and uncovering information that directly concerns their biological relatives as well as themselves. This familial quality of genetic information raises ethical quandaries for physicians, particularly related to their duty of confidentiality. In this article, the American Medical Association's Council on Ethical and Judicial Affairs examines the informed consent process in the specific context of genetic testing, giving particular consideration to the handling of information that has consequences for biological relatives. Furthermore, it addresses the question of whether physicians' obligation to warn biological relatives ever should override the obligation to protect patient confidentiality.