 Informed consent is currently treated as the core of bioethics. In clinical practice, the doctrine of informed consent rose to dominance during the course of the 20th century. It replaced a medical ethos founded on trust in physicians’ decisions, often on the assumption that “doctor knows best”, with an ethos that sought to put patients in charge of their own care. In medical research, the influential Nuremberg Code responded to the cruelty of Nazi experiments stipulating: “The voluntary consent of the human subject is absolutely essential”. But why should we require informed consent, e.g. when it comes at a cost to the individual’s health? What is the content, the scope, and the status of that requirement? How does informed consent in bioethics, the focus of the present entry, relate to consent in sexual ethics, business ethics, and political philosophy?