Population dynamics have a huge impact on social, economic and political processes in different countries, therefore it is extremely important to understand trends and changes in population movements. Through the concepts of birth rate, mortality, immigration and emigration and their consequences of population reproduction and depopulation, the goal is to get a broader picture of population dynamics in the Republic of Croatia and the EU. Current trends in population movements in general in developed countries, including in Croatia and the EU, is a reduction in the mortality rate, which ultimately leads to an aging population. Europe is also facing a general trend of population loss. Some countries of the European Union, such as Germany, Italy, Spain and Poland, are also recording a decrease in the number of inhabitants and a negative rate of natural increase. Various factors, such as urbanization, migration, changes in family values and socioeconomic conditions, affect the demographic picture of the continent. In order to face these challenges, governments and institutions are implementing various policies and measures. This includes encouraging pro-natal policies, such as financial support for families, parental leave and services for children.