The specter of biological warfare (BW) looms large in the minds of many Americans. The US government has required that emergency response teams in more than 100 American cities be trained by the year 2001 to recognize and contain a BW attack. The US military is requiring active duty soldiers to receive immunization against anthrax. Dermatologists need not feel helpless in the face of a potential BW attack. Many potential agents have cutaneous manifestations that the trained eye of a dermatologist can recognize. Through early recognition of a BW attack, dermatologists can aid public health authorities in diagnosing the cause so that preventive and containment measures can be instituted to mitigate morbidity and mortality. This article reviews bacterial, viral, and toxin threat agents and emphasizes those that would have cutaneous manifestations following an aerosol attack. We conclude with clues that can help one recognize a biological attack.