The outbreak of SARS (Severe acute respiratory syndrome), an atypical pneumonia, has received much attention and coverage by the media and has consequently had a high impact on the public. The infectivity and route of transmission of the disease appear unusual, and it turned out to be a highly relevant threat for medical staff. This monograph provides comprehensive information on the newest insights into the SARS epidemic and the responsible infectious agent. Background information on Coronaviridae (coronavirus/torovirus) and coronavirus/torovirus-associated infections in humans and animals is also given.