Monetary aggregates are combinations of different elements that are part of the money supply. The composition of the monetary aggregate is the one that determines its effectiveness, and the structure of monetary aggregate depends on institutional and financial structure of the economy. The financial system is one of the most important systems of each country whose role is to mobilize all funds which may be used in the form of credits and then transform them from savers to those who need it for consumption. For normal functioning of the economic, it is necessary to achieve a certain level of money supply, and any disturbance or threat in the circulation of money will be reflected in the actual movement of the economy. Monetary aggregates can be divided into several groups with regard to the ability to convert one form of money into another or conversion from one function to another. The money supply in the Croatia consists of real money in circulation, reserves and other deposits from banks, and the right to issue the primary money has only and exclusively the Central bank of Croatia. Monetary aggregates in Croatia are: primary money M0, money supply M1, total liquid assets M4 and net domestic assets.