Abstract The right to self-determination is a recognised principle of international law which affects the EU’s relations with its neighbouring countries. After a brief introduction to the principle and its different implications for the EU’s southern and eastern neighbours, the relevant case law of the Court of Justice of the European Union is analysed. It is argued that the Court failed to elaborate upon the substantive consequences of the right to self-determination. Nevertheless, it imposed significant limits to the EU’s Realpolitik. In particular, the case law implies that the EU cannot simply assume the de facto application of its international agreements with respect to non-self-governing territories. At the same time, it appears that the implications of the right to self-determination are often minimised in practice in order to accommodate as much as possible the political sensitivities of neighbouring countries.