The use of deception in research is generally permitted so long as participants are debriefed at the conclusion of their participation. Several authoritative research ethics guidelines allow investigators to omit debriefing under certain circumstances, however. Here we examine various justifications for forgoing debriefing in deceptive research, including concerns about subject pool contamination, the risk that revealing the deception will be harmful or distressing to participants, and issues of practicability. We conclude that, contrary to current practice, omitting debriefing is ethically acceptable (...) only when debriefing is impracticable, the deception is innocuous, and no reasonable person would object to involvement in the research. (shrink)