The nuclear threat is an invisible threat whose adverse effects may be delayed for days to years depending on the dose. The risk to victims and responders varies by the route of exposure (that is, internal vs. external) and the type of ionizing radiation released (alpha, beta, gamma, or neutrons). In some respects, radiological weapons offer a unique advantage to healthcare providers. Instruments designed to check for their presence are readily available. This is not the case with chemical and biological agents.