Severe acute respiratory syndrome (SARS) emerged in southern China in late 2002. It first spread within Guangdong Province and then to other parts of China. Via air travelers, it quickly reached various countries around the globe, causing several major hospital outbreaks. Within weeks, the causative agent, a previously unknown coronavirus (SARS-CoV), was identified, thanks to an unprecedented international effort led by the World Health Organization (WHO). Its origin was quickly traced to wild animals traded locally for culinary purposes. Masked palm civet and some other species seem to have acted as intermediate hosts. Since then, SARS-like coronaviruses were found in different bat species in China and elsewhere, and bats are now regarded as the wildlife reservoir for SARS-CoV. Fortunately, the SARS outbreak could be contained within months. Until July 2003, it had caused 8096 cases, with 774 deaths. Once adequate measures such as isolating patients and quarantining their contacts were strictly adhered to, further transmission between human beings could be interrupted. SARS is an example of how rapidly an infectious agent can spread in the modern world. At the same time, it should serve as a showcase of how international cooperation and modern science can help to combat the spread of infectious diseases.