The problem of this paper is the presentation of the relations between the Republic of Croatia and the European Union and the introduction of the euro as the legal currency of payment in the Republic of Croatia. Namely, the European Union has become a target for many European countries, including the Republic of Croatia. After many years of negotiations, the Republic of Croatia became a member of the European Union in 2013. By joining this Union, this country has committed itself to complying with all the conditions imposed by the Union and will introduce the euro as the legal currency of payment, although it has not specified when it will be. Therefore, the main goal of this paper was to state and explain the advantages and disadvantages of the introduction of the euro in the Republic of Croatia. After the described development of the Europe and institutions of European Union, it is described euroization and the process of introducing the euro into the country were described. After that, the advantages and disadvantages of the introduction of the euro in the Republic of Croatia were explained in detail. From this paper it can be concluded that the introduction of the euro had a number of advantages for the Republic of Croatia. This would strengthen its competitiveness and improve economic growth and development. That is why the Republic of Croatia must continue to implement its policy and, over time, introduce the euro as the legal currency of payment.