The requirement of informed consent (IC) to medical treatments is almost invariably justified with appeal to patient autonomy. Indeed, it is common to assume that there is a conceptual link between the principle of respect for autonomy and the requirement of IC, as in the influential work of Beauchamp and Childress. In this paper I will argue that the possible relation between the norm of respecting (or promoting) patient autonomy and IC is much weaker than conventionally conceived. One consequence of this is that it is possible to exercise your autonomy without having the amount of and the kind of information that are assumed in the standard requirement of IC to medical treatments. In particular, I will argue that with a plausible conception of patient autonomy, the respect for and the promotion of patient autonomy are in certain circumstances better protected by giving patients the right to give their negatively informed consent to medical treatments.