After decades of work on laying the foundations for its introduction, the euro was accepted as the common currency of the European Union in the 1990s. The currency entered actual circulation at the beginning of 2002, making it legal tender in 12 EU member states. According to data from the European Commission, around 340 million citizens in the euro region currently use the euro as their official currency. Since the acceptance of the single European currency is a contractual obligation of all EU members, the European Monetary Union includes 19 of the 27 (current) EU members, and their number will continue to grow. On July 10, 2020, the Republic of Croatia entered the ERM-2 exchange rate system, the rules of which it followed for two years in a row, and on January 1, 2023, it will introduce the euro. The introduction of the euro as the official currency brings a series of changes that will have both positive and negative effects on the Croatian economy. Bearing the above in mind, this paper explains the reasons for the creation as well as the goals of the European Monetary Union, the positive and negative effects of the introduction of the euro as a common currency, both theoretically and practically on the examples of the current members of the European Monetary Union, and presents the very process of introducing the euro as an official currency in Republic of Croatia.