A CONTAMINATING SPRAY: Brucellosis is a zoonosis due to a bacteria of the Brucella. B. melitensis species and is the principle agent of human brucellosis. The interest of Brucella as a biological weapon resides in the fact that transmission through a spray is possible, as has been reported with human contamination during abortion of infected animals or bacterial spraying in laboratories. The bacteria is highly contagious. It is suggested that 10 to 100 bacteria would be sufficient to produce a contaminating spray for humans. THE MENACE: In 1954, B. suis was the first infectious agent used as a biological weapon in the United States. Several other countries have been suspected of studying the agent as a biological weapon, but to date, no use of Brucella in a bioterrorist attack has been reported. THE EXTENT OF RISK: Brucella, and notably B. melitensis and B. suis, are considered as agents unlikely to be used as biological weapons: their incubation is long, the majority of infections are asymptomatic and mortality is low. However, the morbidity of this agent should not be underrated since it leads to chronic and disabling pathologies.