The thought of an outbreak of disease caused by the intentional release of a pathogen or toxin in an American city was alien just 10 years ago. Many people believed that biological warfare was only in the military's imagination, perhaps to be faced by soldiers on a far-away battlefield, if at all. The “anthrax letters” and the resulting deaths from inhalation anthrax have changed that perception. The national, state, and local governments in the United States are preparing for what is now called “not if, but when and how extensive” biological terrorism. In contrast to the acute onset and first-responder focus with a chemical attack, in a bioterrorist attack, the physician and the hospital will be at the center of the fray. Whether the attack is a hoax, a small food-borne outbreak, a lethal aerosol cloud moving silently through a city at night, or the introduction of contagious disease, the physician who understands threat agent characteristics and diagnostic and treatment options and who thinks like an epidemiologist will have the greatest success in limiting the impact of the attack. As individual health care providers, we must add the exotic agents to our diagnostic differentials. Hospital administrators must consider augmenting diagnostic capabilities and surveillance programs and even making infrastructure modifications in preparation for the treatment of victims of bioterrorism. Above all, we must all educate ourselves. If done correctly, preparation for a biological attack will be as “dual use” as the facility that produced the weapon. A sound public health infrastructure, which includes all of us and our resources, will serve this nation well for the control of the disease, no matter what the cause of the disease.