The common law and federal regulations create overlapping legal regimes that require researchers to obtain the informed consent of most human subjects of medical research. The fast-growing field of biomedical research generally, and stem cell research in particular, gives rise to a range of unresolved and contested legal issues concerning the extent and implementation of the informed consent requirement. This Article identifies and assesses a series of these: (1) Must researchers obtain the informed consent of participants in nontherapeutic research not covered by federal research regulations? (2) As part of the process, must researchers disclose their financial interests in their projects? (3) Must informed consent be obtained before researchers use tissues stored in tissue banks? (4) Must informed consent be obtained from both gamete donors before research use may be made of a stored human embryo? The Article argues that these questions can be best resolved by focusing the analysis on the core value of subject autonomy that underlies the principle of informed consent.