The quinquennial Nuclear Non-Proliferation Treaty (NPT) Review Conference represents a highly important event from the perspective of the EU Common Foreign and Security Policy (CFSP). Though not a party to the treaty itself, the EU has made a consistent effort since the 1990s to coordinate the positions of its member states and achieve higher visibility in the NPT review process. The aim of this article is to examine the role of the EU in the 2015 NPT Review Conference deliberations. Drawing on on-site observations, statements and in-depth research interviews, it argues that the recent institutional changes notwithstanding, the influence of the EU as a distinct actor in the NPT context remains very limited, and the EU’s common position is in bigger disarray than ever before. This year’s Review Conference demonstrated the widening rift between the member states, in particular in the area of nuclear disarmament and the related issues. The inability to maintain a coherent common position limits the EU ‘actorness’ and impedes its striving for relevance in the NPT forums. The dynamics outlined in this article further highlight the limits of the EU CFSP in security matters in which the national positions of individual member states are as divergent as in the case of nuclear disarmament.