Notwithstanding requirements for scientific/social value and risk/benefit proportionality in major research ethics policies, there are no widely accepted standards for these judgments in Phase 1 trials. This paper examines whether the principle of clinical equipoise can be used as a standard for assessing the ratio of risk to direct-benefit presented by drugs administered in one category of Phase 1 study--first-in-human trials involving patients. On the basis of the supporting evidence for, and architecture of, Phase 1 studies, the articles offers two provisional conclusions: (1) the risks of drug administration in such trials cannot generally be justified on therapeutic grounds but by appeal to the social value of the research; and (2) a framework for adjudicating the ratio of risk/social-value must be developed.