The emergency department (ED) is an essential component of the public health response plan for control of acute respiratory infectious threats. Effective respiratory hygiene in the ED is imperative to limit the spread of dangerous respiratory pathogens, including influenza, severe acute respiratory syndrome, avian influenza, and bioterrorism agents, particularly given that these agents may not be immediately identifiable. Sustaining effective respiratory control measures is especially challenging in the ED because of patient crowding, inadequate staffing and resources, and ever-increasing numbers of immunocompromised patients. Threat of contagion exists not only for ED patients but also for visitors, health care workers, and inpatient populations. Potential physical sites for respiratory disease transmission extend from out-of-hospital care, to triage, waiting room, ED treatment area, and the hospital at large. This article presents a summary of the most current information available in the literature about respiratory hygiene in the ED, including administrative, patient, and legal issues. Wherever possible, specific recommendations and references to practical information from the Centers for Disease Control and Prevention are provided. The "Administrative Issues" section describes coordination with public health departments, procedures for effective facility planning, and measures for health care worker protection (education, staffing optimization, and vaccination). The patient care section addresses the potentially infected ED patient, including emergency medical services concerns, triage planning, and patient transport. "Legal Issues" discusses the interplay between public safety and patient privacy. Emergency physicians play a critical role in early identification, treatment, and containment of potentially lethal respiratory pathogens. This brief synopsis should help clinicians and administrators understand, develop, and implement appropriate policies and procedures to address respiratory hygiene in the ED.