In December 1998, 2,700 metric tons of industrial waste containing high levels of mercury and other metals and possibly other toxic compounds were shipped illegally from Taiwan to Sihanoukville, Cambodia. There the waste was unloaded and transferred to a nearby inland dumpsite. An estimated 2,000 Sihanoukville residents were exposed to the waste occupationally or environmentally, and at least six deaths and hundreds of injuries have been associated with the incident. The authors describe the human exposures and associated morbidity and mortality, recount the medical and public health response, and consider the issues complicating epidemiologic analysis of the incident. They also consider the major issues highlighted by the incident, including the trade in toxic waste between developed and less developed countries, the factors that shape emergency public health responses in resource-poor environments, and the importance of prevention and preparedness in containing emergencies in developing countries.