A requirement to uphold the confidentiality of information shared in the physician-patient relationship is a central tenet of medical professionalism that, while at risk and undermined in various ways in modern medicine, has been consistently endorsed from the time of Hippocrates. This essay addresses confidentiality less in medical professionalism terms than in terms of the roots and impact of medical confidentiality in society more broadly. We investigate, in particular, the moral basis of confidentiality beyond a requirement of professionalism, contextual features of societies (institutions, roles, and cultures) that may affect confidentiality, and social expectations of—and challenges to—confidentiality.