This article provides a brief overview of the legal aspects of EU military crisis management operations, which, together with the EU’s civilian missions, are the main manifestation of the EU’s Security and Defence Policy. After the introduction (I), section II addresses the EU law aspects, section III covers the main international law aspects and section IV deals with domestic law aspects, including both the law of sending States and of the host State. Section V draws some conclusions and offers some reflections on the legal aspects of EU military operations and their role and importance. The author concludes that the EU has a well established legal framework for its military operations, which is soundly anchored in the EU Treaty, elaborated in practice and firmly based in and in compliance with international law. He also submits that the Lisbon Treaty reinforces this legal framework on several points and that the EU can rely on a number of mechanisms that should enable it to address most legal challenges that may arise.