In recent years, there have been signs of an increase in the cost of various construction projects, which indicates that the changes in the construction cost index are also increasing. In today’s situation, when joint international construction projects, such as Rail Baltic, are implemented in the European Union, the question arises about the fluctuations of construction costs not only in Latvia but also in other European Union countries. In order to compare the indices of construction costs in different countries of the European Union, it should be concluded that these indices are created considering different criteria depending on different categories of construction works, such as residential buildings, engineering structures and other groups. Most of the member states of the European Union publish construction price indices, which often differ both in terms of their type and purpose, as well as in terms of the volume of construction activity and the items included in the creation of the index. As a result of the study, the authors conclude that the European Union member states, when developing a construction price index calculation system, are recommended to use the international or national classification, indicating that the national classification systems must be compatible with the international classifications.