The European Union has become one of the most important international actors in the fight against terrorism. After 9–11, it has adopted a broad spectrum of measures that are being implemented in all three pillars and member countries. The article shows the gradual evolution of measures against international terrorism by the EU in relation to the developing threat. It represents an analysis of the understanding of terrorism at the EU level, evolution of the EU Action Plan since 2001, the role of terrorism in the European Security Strategy, the role of the EU Counter-Terrorism Co-ordinator and SITCEN, the EU Counter-Terrorism Strategy etc. The article shows, that despite all these measures, the threat from terrorism remains one of the key European problems and challenges. It will take time and serious efforts to remove many existing problems and dilemmas.