The purpose of this paper of research was to investigate with scientific methods what are excise duties in the tax system of the Republic of Croatia, their legislative framework and to compare excise rates and the way tobacco products, alcohol, alcohol drinks, energy and electricity are taxed before and after entering the European Union and also to compare excise duties with the rest of the member states of the European Union. At the very end take the latest information on the amount of the excise income and explain their great importance in the economy of the Republic of Croatia. Because 2016. they account 20,5 percent of tax revenue of the state budget, after VAT revenue they are the most important group. The highest revenues generate excise duties on energy and electricity even more than a half by 55,3 percent, followed by excise duties on tobacco products, accounting for 30,3 percent of total excis revenue. There is a trend of growth so we can expect further gowth of excise duties as well as the excise revenue. However, there is also the influence of the gray economy which can lower further growth of revenue. Therefore, we can say that it is necessary to carry out an appropriate good policy as this would not happen because it is one of the most important tax revenues of the Republic of Croatia.