This Master thesis is divided into two parts: in the first part we define terms like open access and institutional repositories, also we explain different initiatives and statements that initiated developing open access. After that, we will say something about the development of institutional repositories in Croatia. Furthermore, we explain how Dabar was created and the part it plays in the development of institutional repositories in Croatia. The fundament of the second part in this thesis consists of analysis and comparison of five different institutional repositories of chosen academic institutions: University of Zagreb School of Medicine Repository, Repository of the Humanities and Social Sciences, Repository of Faculty of Organization and Information, Repository of the Faculty of Economics in Osijek, Repository Faculty of Law University of Zagreb. In these institutional repositories we first analyse the design of internet sites, the type of stored documents, which criteria is used to browse repositories and finally visit and publication statistics. Repositories of Faculty of Humanities and Social Sciences and School of Medicine are run by their own institution and exist for a longer period so we will compare previous works on these topics and highlight changes that occured. Unlike repositories of Faculty of Humanities and Social Sciences and School of Medicine that are organised by their own libraries, other repositories are developed by Dabar and they are more recent. Thesis ends with comparison of obtained results.