Humans are susceptible to microbial infections from many sources. Biological warfare is the use of microbial forms of life to diminish the capabilities, disrupt the organization, and terrorize the noncombatant population of an adversary. This form of warfare has been used throughout history and has gained renewed interest with the current use of asymmetrical warfare. The civilized world has condemned its use by the implementation of treaties specifically against it. This is a brief review of some of the more easily used biological agents such as anthrax, plague, tularemia, Q fever, and smallpox. Each agent's biology, infectious route, and disease course will be discussed. Possible delivery systems and signs of outbreak will also be reviewed. There are few real neurosurgery-related implications in biological warfare. Neurosurgeons, as members and leaders of the healthcare community, must have the ability to recognize and initiate treatment when biological agents have been deployed. If there is widespread use of these inhumane agents, the neurosurgical community will not be able to practice the surgical art for which we have trained. New knowledge must be acquired so that we can best serve our patients and communities during times of extreme need.