Anthrax is a disease caused by Bacillus anthracis, a gram-positive, aerobic, spore-forming rod. It is also used as a biological weapon. The primary care physician will be the public's first line of defense in the event of a widespread anthrax exposure and will play a crucial role providing postexposure prophylaxis. Understanding the disease process will allow the primary care physician to play an essential role in protecting and educating the public. Accurate diagnosis and quick treatment will save many lives and help calm the panic following a biological attack.