Introduction: Biological attack a phenomenon which has seriously started in the 20th- century and is expanding every day. Plague agent is one of factors listed as a biological weapon by the disarmament convention. Therefore, the risk of biological or bioterrorism applications is probable and serious. The purpose of this study was to update health professionals' information on plague and bioterrorism aspect of this disease.

Methods: This article is a literature review written based on search on articles from library and internet resources (1990- 2016).

Results: More than 2,000 species of bacteria have been identified in three main groups of bacillus (rod-shaped), cocci (round and oval), and spiral. But only about 100 of them are known as pathogens and Less than 10 species are used as biological agents for military application and one of them is plague agent. Yersinia pestis is a Gram negative, rod-shaped, anaerobic, member of the enterobacteriaceae family, and if be painted by Colors Wright, Giemsa or Leeson will be seen bipolar under a microscope.

Conclusion: Nowadays, in spite of the progresses made in science and technology, human knowledge is relatively incapable to anticipate the time and place of biological attacks. Therefore, being prepared and ready for its unavoidable occurrence is necessary. So, regarding the importance and necessity of readiness, officials and experts have to make an effort and plan against these hazards.

Introduction: Biological attacks are a phenomenon that started on a serious note in the twentieth century and such weapons are being developed every day.The agent of plague is one of those listed as biological weapons by the Weapons Convention. So, the danger of its biological or bioterrorist applications by the enemy is possible and poses a serious threat. The purpose of compiling this article is to update information of health personnel about plague and the bioterrorist aspect of this disease.

Methods: This article is a review study which had been undertaken based on articles searched from the library and the internet (1990–2016).

Results: More than 2000 species of bacteria have been identified in three main groups of bacillus (rod-shaped), cocci (round and oval) and spiral (helical) but only approximately 100 species have been identified as pathogenic and less than 10 species are used as suitable biological agents for military application and the plague agent is one of them. Yersinia pestis is a type of gram-negative anaerobic coccobacillus from the Enterobacteriaceae family and if it is stained with Wright, Giemsa or Wayson it can be seen as bipolar under a microscope.

Conclusion: Nowadays, despite development of science and technology, humans are not able to predict time and location of this type of attack. So, we should be prepared for this unavoidable eventuality. Considering the importance and necessity of preparing to deal with attacks, authors of such studies and professionals should consciously plan and try to prepare against these dangers.