||This thesis depicts monetary integration of the European states from the second half of the nineteenth century to the period after the First World War, which was taking place against the background of the then metallic monetary systems. The aim is to provide a comprehensive view of the historical developement of integrating tendencies and to reveal the reasons of its successes and failures. The first part provides a brief theoretical introduction, the stress is putted especially on the theory of optimal currency areas. The remaining parts deal with monetary unions of the surveyed period. Firstly we look at the ways in which national and multinational monetary unions of the nineteenth century were realized. The spontaneous adoption of the gold standard by the majority of countries in the 1870s created world monetary union based on a system of fixed exchange rates. Finally we focuse on the Austro-Hungarian monetary union.