A biological weapon is a device used to intentionally cause disease through dissemination of bacteria, virus or microbial toxin. Depending on the microbe or toxin, resulting disease may or may not be contagious. Biological terrorism, then, is the use of a biological weapon against civilian populations for purposes of creating terror. Generally, the result of use of a biological. weapon is an epidemic. The microbial agents required to make some of the biological weapons are widely available, and associated technology is also obtainable given its legitimate use for agricultural, pharmaceutical or other purposes. Although, food, water or insects are potential vehicles for transmission of biological weapons, aerosol dissemination has greatest capacity to cause the disease. This is a review article.