Informed prospective consent for clinical resuscitation research may not be possible. Deferred consent is an untenable notion. Consent to continue in research cannot be used to support a claim that there was, or would have been, consent to the initiation of research. The conditions for the justifiability of resuscitation research without informed consent are: a) patient is comatose; b) lifesaving treatment must be given immediately; c) given all available evidence, there is reason to believe that the probability of death or severe deficit with experimental or control therapy is not greater than the probability of death or severe deficit on usual therapy; d) given all available evidence, there is reason to believe that the probability of normal or near-normal outcome is greater on experimental or control therapy than on usual therapy; and e) the study can provide evidence on whether there is a significant difference between experimental and control therapies in the incidence of normal or near-normal survival.