生物武器，旧称细菌武器

在人类战争史上，细菌武器的使用由来已久。据文献记载，最早使用细菌武器的案例系公元前1200年，赫梯人将带菌的尸体抛射到敌方土地上。1349年，蒙古人围攻克里米亚半岛上的卡法城（Kaffa）时，由于城坚难摧，攻城部队又受到由中国向西蔓延的鼠疫大流行的影响，他们便把鼠疫病死者从城外抛到城内，结果使保卫卡法城的许多士兵和居民染上鼠疫，不得不弃城西逃。

第二次世界大战时日本军曾以中国东北的平房地区作为满洲第731部队的驻地，针对冻伤、病原体毒力回归等课题开展一系列以人为实验动物的试验，借此改良用于侵华战争及其他战线的生物武器。

Biological warfare (BW)—also known as germ warfare—is the use of biological toxins or infectious agents such as bacteria, viruses, and fungi with the intent to kill or incapacitate humans, animals or plants as an act of war. Biological weapons (often termed "bio-weapons", "biological threat agents", or "bio-agents") are living organisms or replicating entities (viruses, which are not universally considered "alive") that reproduce or replicate within their host victims. Entomological (insect) warfare is also considered a type of biological weapon. This type of warfare is distinct from nuclear warfare and chemical warfare, which together with biological warfare make up NBC, the military acronym for nuclear, biological, and chemical warfare using weapons of mass destruction (WMDs). None of these are conventional weapons, which are primarily due to their explosive, kinetic, or incendiary potential.