Deliberate contamination of food with biological agents has already been perpetrated in the USA. The US food supply is increasingly characterised by centralised production and wide distribution of products. Deliberate contamination of a commercial food product could cause an outbreak of disease, with many illnesses dispersed over wide geographical areas. Dependent on the biological agent and contaminated food, such an outbreak could either present as a slow, diffuse, and initially unremarkable increase in sporadic cases, or as an explosive epidemic suddenly producing many illnesses. Preparedness for a bioterrorist event affecting the food supply, therefore, entails augmentation of the traditional public-health infrastructure to enhance disease surveillance, accelerate capacity of laboratory detection, rapidly investigate and control outbreaks, and develop capacity for response to mass-casualty disasters.