There are many definitions of terrorism and numerous examples of the use of explosives and small arms, especially against civilians and with the objective of instilling fear. Although chemical and biological agents have only rarely been used by terrorists, there has recently been much concern about the threat of bioterrorism and the role of future health personnel in counteracting it. Rational setting of priorities requires the balance of risks against benefits in prevention and preparedness. Adverse effects of preparedness include inappropriate warnings, diversion of resources from other public health measures, both in the United States and overseas and constraints on civil rights. It is argued that the US should counteract the threat of bioterrorism by dealing with its root causes and by strengthening civil rights, international arms control and international law rather than by a self-defeating 'war on terrorism'.