In the referendum of 23 June 2016, the 51.89% majority of the British who decided to vote opted for the exit of their country from the European Union. This paper presents the main threads in the debate concerning, on the one hand, the reasons for Brexit and, on the other hand, its potential consequences for the United Kingdom and the EU. The vote for Brexit was determined by long-term factors (the specific character of the country’s political and economic systems) as well as short-term ones (the rising wave of immigration and the erroneous assumptions in the strategy of the pro-Europe camp). The main factor determining the scale of Brexit’s consequences will be the result of negotiations, and thus the status of the United Kingdom in its relationships with the EU to be established in the course of negotiations, as well as political, economic, and social practices. Most analysts share the opinion that these consequences will be negative. This applies in particular to economic issues and the territorial integrity of the United Kingdom.