Recently, biological weapons (BWs) prepared with pathogenic microorganisms, toxins and biological vectors have been used maliciously for biological warfare, bioterrorism and/or agroterrorism by hostile countries and terrorists. In this review, historical background of disease and malicious use of BWs pathogenicity of microorganisms, advanced methodology involved in laboratory diagnosis, and prevention and control of anthrax (Bacillus anthracis), plague (Yersinia pseudotuberculosis subs. pestis), glanders (Burkholderia mallei), and smallpox (Variola virus) which have been abused for biological warfare or bioterrorism were discussed. In addition, the pathogenicity of microorganisms and the methodology needed to diagnose and control 6 diseases identified by WHO/CDC, ie., smallpox, inhalation anthrax, pneumonic plague, botulism, tularemia, and hemorrhagic fevers that would wreak havoc if terrorists successfully disseminated the germs by air were described.