Bio-terrorism involves using biological agents/toxins with the intent to intimidate or coerce a government or civilian population to further political or social objectives, usually leading to deaths or illnesses of humans but also of plants/animals. Their use would probably initially be considered as a natural or unintentional event, especially in case of live biological agents. Moreover, a natural occurring disease outbreak could have the same destructive outcome as an efficient biological weapon. There is a need for proper differentiation between natural and intentional events although in the first stages the medical response should be similar; however, the course of incident management would take different paths later on. Biological agents’ investigation of dangerous pathogens, from natural unusual outbreaks or bioterrorist attacks/other intentional use, imply the collaboration of different institutions with responsibilities in public health but also in national security and defense. The National Security and the Defense System institutions think mainly in security terms while national health care system institutions think principally` in medical care/prevention terms. These two ways of acting have to be combined in order to deal properly with hazardous biological agents.