Even with the technologic sophistication available in the United States today, effectiveness in dealing with a bioterrorist event is limited. Current surveillance systems may be inadequate to detect attacks. Because the onset of illness after exposure to an agent is delayed, even the time and location of the attack may be vague. In addition, most of the medical community is unfamiliar with many of the high-threat diseases, so identification of the problem may be further delayed. Many of us who are involved in studying the many aspects of bioterrorism believe that it is not a question of if such an event will occur but rather when, as well as which agent will be used and how extensive the damage will be. Given the enormity of what is possible, we must prepare for a potential nightmare.