Respect for autonomy is an important moral principle within medical ethics. However, the question of whether the normative importance of respect for autonomy is derived from other moral principles (such as welfare) or has independent moral value is debatable. In this paper it is argued that the normative importance of autonomy is derived from both welfare and non-welfare considerations. Welfare considerations provide two types of reason to respect autonomy, one related to the role of autonomy in creating welfare and one (...) related to its role in constituting welfare. In addition, autonomy seems to have normative importance that is unrelated to welfare considerations. This type of normative role is difficult to defend within medical ethics, because most non-welfare justifications of autonomy work for only a proportion of the autonomous decisions that patients make and give no clear guidance on how to respond to autonomous yet welfare-reducing treatment requests. A recent account of autonomy (Stephen Darwall’s “demand” account) provides a nuanced defence of autonomy that does not rely on welfare considerations. Darwall’s approach seems to work well within medical ethics and provides a principled explanation of how to respond to autonomous patient requests for treatment options that may not be in their best medical interests. It is argued that to fully respect autonomy within a medical consultation, practitioners must consider non-welfare autonomy as well as instrumental and intrinsic welfare-related autonomy. (shrink)