Cryonics is the low temperature preservation of people who can no longer be sustained by contemporary medicine in the hope that future medicine will make it possible to revive them and restore their health. A speculative practice at the outer edge of science, cryonics is often viewed with suspicion. In this paper I defend two theses. I first argue that there is a small, yet non-negligible, chance that cryonics is technically feasible. I make the case for this by reference to what we know about death and cryobiology, and what we can expect of future nanorobotics. I further argue that insofar as the alternatives to cryonics are burial or cremation, and thus certain, irreversible death, even small chances for success can be sufficient to make opting for cryonics a rational choice. Finally, I reply to five objections.