In this bachelor thesis, the legal-political process of leaving the United Kingdom from European Union (Brexit) and the impact on the global economic and financial system has been explored. Negotiated withdrawal negotiations must be completed within two years of the moment of activation of Article 50 by the United Kingdom. If no agreement is reached in that period, the existing Treaties will cease to be applied to the withdrawing state. In a legal and political sense, the European Union will provide guidelines on the basis of common interests of the European Union and its member states and set out the general principles that the EU will adhere to during the negotiations. The day after the referendum on which the UK citizens decided to leave the EU, there were strong disruptions in the economic and financial sector which was the most reflected to the value of the British pound, which had the highest decline in the last 31 years and that decline was felt at all relevant and less relevant global stock exchanges. The range of estimates for the potential economic consequences of a Brexit (derived mostly from forward looking ex ante estimates) is amazingly wide. The most pessimistic study concludes that the UK is about 11.5 percent of GDP worse-off because of EU membership. Conversely, a withdrawal from the EU would mean an increase in British GDP by the same order of magnitude. The other extreme is covered by studies presented in the following section that estimate the possible benefits of the UK’s EU membership to be in the range of 20 percent (GDP per capita) and more. In case of a Brexit, a significant part of this benefit would vanish (depending on post-exit integration arrangements) and thus turn into a cost for the UK.