The last decade has seen a surge in biomedical research advancing the evidence base for the effective clinical management and study of posttraumatic stress disorder (PTSD). The authors review the literature describing ethical issues in conducting PTSD research; controversies over the role of preventive pharmacotherapy for PTSD; and ethical quandaries in the identification, treatment, or empirical investigation of PTSD in postdisaster settings. Findings are synthesized within an ethics framework that utilizes major constructs in the biomedical literature: beneficence/nonmaleficence, informed consent, and autonomy. Gaps and weaknesses in the current evidence base are highlighted. The authors conclude by considering priorities for future empirical ethics investigation in this field.