The United States armed forces have recognized the military value of vaccines against biological threats. However, vaccines cannot be considered a first line of defense against bioterrorism for the general population as they can be for the relatively small military population. Smallpox and anthrax, which pose the greatest risk for causing large numbers of casualties in the event of an effective release by a terrorist group, are at the top of the list of threat agents. One vaccine in development that is of great importance to civilian biodefense is the vaccinia virus vaccine made in cell culture. A new national stockpile of vaccinia vaccine is urgently needed to respond to the possible threat of a deliberate release of smallpox virus. Anthrax is the second threat that requires a major research and development effort to meet civilian needs. Providing the exposed population with antibiotics followed by vaccination could be lifesaving for exposed persons who would otherwise become ill with untreatable inhalation anthrax in the subsequent few weeks after attack. However, the current anthrax vaccine multiple dose requirement is a drawback for civilian use. Studies in progress may find ways to allow modification of the schedule. The value of vaccinating law enforcement and emergency response personnel who must respond to threats depends on the nature of their work and the immediacy of the threat. Laboratory personnel who must work with unknown materials and with high concentrations of known infectious materials must be vaccinated. These are additional justifications for moving ahead with a vigorous development program for anthrax and smallpox vaccines. 1 table and 3 references.