The aim of this final work is to explain the concept of customs , it’s division and history of the Croatian custom system before and after joining the European Union. Customs are the oldest and the most important instruments of foreign policy of every country, and there fore it can be said that part of the duties of state policy. Through the historical development of the customs had different meanings, but similarly categorized and classified as today. The objectives of the customs are protection and development of domestic production, and therefore the Croatian customs system had to be changed, amended and improved. Since Croatia became independent in 1991 and the modern state had to regulate the customs system and legislation which are relevant for customs. Any state including the Republic of Croatia has customs procedures and customs tariff which are explained in the third chapter. A condition of entry into the European Union was to customs system of Croatian customs harmonize with the EU system. All countries that are full members of the European Union and become a member of the customs union. Customs Union allow the free movement of goods, services, capital and people within the borders of the European Union. Customs tariffs in all EU Member States is common, while the tariff rate is determined by each of its customs territory. Customs documents in the European Union are unique customs declaration, declaration of customs value of goods, Carnet TIR and ATA carnet, which are explained in chapter four. By joining the European Union, the Republic of Croatia becomes 28 full legal member. And so the last chapter describes the changes that have occurred in joining the EU, such as the organization of the customs service, outlook in customs free zones, E-Customs. Croatia will 01/07/2015. year to apply for entry into the Schengen area, so the Croatian borders become external borders of the European Union.