The outbreak of Severe Acute Respiratory Syndrome (SARS) clearly illustrates that the emergence or re-emergence of infectious diseases is a constant threat. In late February, the world became aware of the existence of SARS in Vietnam after an alert from WHO scientist Dr Carlo Urbani (who later died from the disease). However, SARS originated in southern China in November 2002. Globally, the total number of confirmed cases has now reached 8221 (as at 27 May 2003). While patients with SARS have been identified in more than 30 countries, the majority of cases have occurred in China (7648), including Hong Kong (1728) and Taiwan (596). To date, control of the SARS outbreak has focused on preventing its transmission, and there has been an emphasis on the development of diagnostic tests to accurately identify the virus in patients with suspected SARS infections. However, a number of compounds are currently under investigation as potential treatments for the disease.