To the Editor: We respectfully disagree with Dr. Huddle's opinion, expressed in his March article,1 that political advocacy should not be a physician's responsibility. From the time of Hippocrates, advocacy and service to society have been duties of physicians. Although Dr. Huddle accepts that he has an obligation to advocate on behalf of specific patients, he limits himself to this narrow commitment. What he does not acknowledge is the social contract between society and the medical profession, which gives the latter autonomy and self-regulation in return for fostering the health of society—an activity that, at times, can include political advocacy. Advocacy by physicians does not mean that physicians become politicians. It means that they are sufficiently aware of the determinants of health, as well as problems and resources in the specific communities where their practices are located, to know when a situation requires them to become advocates for the individual or collective well-being of their patients. Physicians are ideally placed to observe the health impacts of socioeconomic factors, which puts them in an advantageous position to promote the health of patients and communities as a professional responsibility. To go farther in political advocacy than is warranted by that professional responsibility is the physician's individual choice, which we maintain should be respected. The kind of behavior that Dr. Huddle proposes, in which physicians turn their backs on their professional responsibilities to the health of their communities, will continue to undermine public trust in doctors and the health care system. Jeannine Girard-Pearlman Banack, MEd PhD candidate, Ontario Institute for Studies in Education, University of Toronto Faculty of Medicine, and research fellow, Wilson Centre, Toronto, Ontario, Canada; [email protected]. Niall Byrne, MA, PhD Professor emeritus, University of Toronto Faculty of Medicine, and coordinator, International Visiting Professors Program, Wilson Centre, Toronto, Ontario, Canada.