Abstract. Terrorism as an information war. The author tries to analyze the phenomenon of terrorism in the field of information war. Terrorists effectively use the environment which is a good place to spread information to the unlimited number of recipients. Moreover, terrorists started to be less dependent from the journalists creating – using Internet – their own media. Therefore the authos notes that terrorism should be treated as a form of information war. It implies that elements, both offensive and defensive, of information war should be the immanent part of the fight against terrorism. Disregarding those elements fosters that terrorists achieve their aims, which can be exemplified by the terrorism attack in Madrid in 2004. The author highlights that the inclusion of the information war to the system of the fight against terrorism is associated with the proactive strategy, which is to prevent the terrorist attack.