Are there limits to respect for autonomy in bioethics?

I discuss the significance of respect for personal autonomy in bioethics with reference to its practical expression: rational informed patient choice. The question is whether, given the apparent practical limitations to this notion, bioethical autonomy should be seen as an absolute. After a historical review of informed consent and its development, I discuss the requirements for informed consent. Some inherent tensions are evaluated, as is the applicability of the notion that in order to be legitimate, autonomy should do some ethical work. Limits to the notion of informed consent are explored with reference to six examples: the right of women to reproductive autonomy; the autonomy of legally minor Jehovah's Witnesses; autonomy in cosmetic surgery; inappropriate treatment; autonomy and human medical research, and euthanasia and other end-of-life options. The discussion is within a South African framework with reference to other jurisdictions and decisions where appropriate. I conclude that whilst some unusual instances of limitation of bioethical informed consent might be ethically justifiable, the arguments presented point to the opposite: the unfounded limitation of informed consent.