Given the low mortality and morbidity of the severe acute respiratory syndrome (SARS) compared with other public health scourges, is the attention devoted to it misdirected? The SARS experience has provided at least 4 enduring lessons. First, by providing a test of the capacity of each part of the public health system, from national to local and hospital responses, it has better prepared the world for the anticipated and much-feared next real pandemic. Second, SARS has reemphasized that from housing, sexual practices, and slaughtering techniques to health care capacity, the situation in other, especially developing, countries affects us. Global cooperation is necessary not only for justice but to ensure our own health. Third, despite trends toward commercialization, easier lives, and self-centered individualism, the response of health care professionals to SARS reaffirmed dedication to caring for the sick even at great personal risks as the core ethical principle of medicine. Finally, SARS also emphasized the importance of the duty of health care administrators and senior physicians to rapidly institute procedures to maximize the safety of frontline physicians and nurses. These lessons will be valuable far beyond the SARS episode.