There is a good deal of biomedical research that does not produce scientifically useful data because it fails to recruit a sufficient number of subjects. This fact is typically not disclosed to prospective subjects. In general, the guidance about consent concerns the information required to make intelligent self-interested decisions and ignores some of the information required for intelligent altruistic decisions. Bioethics has worried about the ‘therapeutic misconception’, but has ignored the ‘completion misconception’. This article argues that, other things being equal, (...) prospective subjects should be informed about the possibility of non-completion as part of the standard consent process if it is or should be anticipatable that there is a non-trivial possibility of non-completion and that information is likely to be relevant to a prospective subject's decision to consent. The article then considers several objections to the argument, including the objection that disclosing non-completion information would make recruitment even more difficult. (shrink)