The recent intensification of EU-NATO dialogue alongside with the major strategic and operational changes within the Common Security and Defence Policy have reopened discussions about the future European security architecture. What is the role of both organisations and what configuration of their relations would be optimal? Will the EU ambition for strategic autonomy make a positive contribution also to NATO or will it lead to further decoupling and fragmentation of the transatlantic bond? The article examines both the challenges and main achievements of EU-NATO relations with focus on the most promising areas of cooperation.