In the last twenty years, digitalization has become an indispensable part of Croatian national cultural policies and programs, which include Croatian libraries. Most libraries recognized the importance of the information age, so digitalization, as part of information and communication technology, has become an indispensable and constructive part of their business, all for the purpose of popularizing library materials, protecting old and rare materials, more precisely originals and increasing the availability of library collections. This diploma thesis, through the theoretical and research part, provides an overview of Croatian digital collections in ten related chapters. The sample consists of Croatian public libraries selected according to the criteria of the central cities of all counties because efforts were made to include the entire territory of the Republic of Croatia, all in order to show the situation in Croatia and its regions. The main goal of this thesis is to determine whether and to what extent Croatian libraries have adapted to the development of modern society and provided the widest possible access to important digital sources and information to users. Also, efforts were made to identify the contents and scope of digital material in a specific cultural institution, organization of digital collections and to assess the quality of digital objects, but also to analyze their user interface. Available digital collections were searched exclusively on the Internet, on the Public Libraries Portal and on the websites of the libraries themselves. Digital collections are shown descriptively, while comparisons of the most important features are shown in tabular form. Most of the central public libraries of Croatian counties have digital collections, which are available in a smaller number of libraries through online catalogs, and in a larger number as segments of the web structure. Some digital libraries are displayed using separate applications designed for just that purpose. A small number of digital libraries have present notes on access and use rights. The most used metadata description standards are Dublin Core and MARC, and most libraries offer the ability to search digital collections. Navigation, visual visibility, and organization of digital objects are of satisfactory quality in most libraries. It has been noticed that the quality of digital objects is higher in the digital collections of libraries in larger cities.