Foreign direct investments are investments that affect the economic, technological and social environment and the volume of trade more than any other flow of capital. As that, they take an important place in strategic planning of a country. Recent trends show that there is a decrease in global foreign direct investment flow, caused by economic instability, political uncertainty and geopolitical risks. However, developing countries take leadership in the global flow of investments. This paper is explaining the main effects of foreign direct investments with the focus on the European Union. It aims to show the differences in approach to foreign direct investments in selected developed European Union economies and selected new Member States, but also shows the importance of economic integration for foreign direct investment. There is a circular effect where direct investments lead to economic growth and economic growth leads to more foreign direct investments. That effect can be seen also in the case of the European Union where developed countries hold more foreign direct investments than new Member States. Being a member of the European Union has represented an advantage for its members, but after United Kingdom has decided to leave the Union, the stability of the Union has come into question. The uncertainties may broaden, if other Member States decide to follow.