The people’s participation in decision-making process is a significant part of Europe’s and the European Union’s history. The institution of referendum plays important role in this context. The main aim of this article is to answer the question of how and in what circumstances referenda are used to decide on a possible resignation from the membership in the European Union (as in the case of the UK referendum) or indirectly – a possible exit from the euro zone (as in the case of the Greek vote on the adoption of financial bailout). An important task in this context is to consider the consequences of such referenda – both for individual countries and for the European Union as whole (also in the context of its flexibility).