Information and communication technology, through its action, conditions the revolution of human work, free time and everyday life of people. In addition, this factor has a significant impact on the change of existing business rules. Governments around the world have recognized its significant role in terms of increasing business efficiency and making administrative work easier. Therefore, it is not surprising that the concept of e-government is the subject of numerous researches both in theory and in practice. Also, in the territory of the European Union, eadministration represents a priority trend in the modernization of public administration. In the Republic of Croatia, such a national system of electronic administration is the e-citizens system, which was implemented with the aim of modernizing, simplifying and speeding up mutual communication between citizens and public administration, but also to increase the transparency of the public sector in the area of public service provision. This paper covers the digitization of the public sector, i.e. the concept of electronic public administration, the field of e-government and its implementation models, as well as an analysis of the national system of electronic administration in the Republic of Croatia, known as e-Citizen, and the development of e-systems in the member states of the European Union.