Ricin is a peptide uniquely present in the seed of Ricinus communis (castor oil plant). It is considered the most toxic, plant-derived protein, and is superseded by the protein botulinum toxin from the bacterium Clostridium botulinum. It has spread from its indigenous Mediterranean and Eastern African regions throughout the tropical areas of the world, used widely as a decorative plant. It can be found in the Southern and East Coast United States. The symptoms of ricin poisoning are initially nonspecific and include fever, abdominal pain, or chest tightness depending on the route of ingestion. After inhalation, ricin causes cell death in the respiratory system and eventual respiratory failure. The Laboratory Response Network (LRN) and the national Centers for Disease Control and Prevention (CDC) has issued guidelines in response to the detection of samples that are thought to contain ricin. Ricin is categorized as a category B biological agent. Detection of ricin in both environmental and biological fluid samples is achieved primarily with enzyme-linked immunosorbent assays (ELISA) with a limit of detection around 100 pg ricin/ml matrix. Improved ELISAs have been developed that utilize laser-induced fluorescence and gold, as well as silver particles, to shorten analysis time and enhance sensitivity. The CDC has enhanced its preparedness and responsiveness to bioterrorism attacks over recent years: (1) increased numbers of epidemiologists have been identified; (2) at least one specialty laboratory that can perform rapid tests for the detection of potential biotoxins was established for each State; (3) communications between the CDC and State agencies as well as first responders and physicians have been optimized; and (4) the number of State public health departments able to receive urgent disease reports 24/7 year round increased from 12 in 1999 to 50 States and the District of Columbia. Figure, photo, and references