Physician advocacy is an action by a physician to promote those social, economic, educational, and political changes that ameliorate the suffering and threats to human health and well-being that he or she identifies through his or her professional work and expertise. According to the American Medical Association, physician advocacy is essential for addressing the social determinants of health. The intersection of medical ethics, legal constraints, and advocacy poses unique challenges for health care professionals. In this article, we will explore physician advocacy from a lens of the principles of medical ethics: beneficence, nonmaleficence, autonomy, and justice.