The possible cutaneous manifestations of infectious biological warfare are multiple and vary depending on the agent used. An ulcerous and/or necrotic syndrome and/or regional lymphadenitis syndrome are possible with anthrax, tularaemia, bubonic plague and emission of trichotecene mycotoxins. A vesiculo-pustular syndrome with fever is provoked by smallpox, melioidosis and glanders. A purpural and/or haemorrhagic syndrome is seen during haemorrhagic fever viruses and septicaemic plague. These cutaneous manifestations are excellent markers that orient and alert when they occur in a context of a situation at risk, when several cases are observed in a usually non-exposed population and with extra-dermatological syndromes. They permit the early initiation of treatment.