This diploma paper analyses the court decisions of the European Court of Human Rights brought in proceeding against the Republic of Croatia, by the aspects developed through the interpretation of the rights contained in Art. 6 of the European Convention on Human Rights. The degree to which the fair trial in the practice of the European Court was implemented in Croatian administrative law and practice was observed. In other words, the direct or indirect influence on administrative adjudication process in the Republic of Croatia, by the Strasbourg acquis, up to today was analyzed. A comprehensive overview of the content is relevant because it shows to what extent public administrative bodies and the Administrative Court of the Republic of Croatia evaluate the European Convention for the Protection of Human Rights and Fundamental Freedoms. Administrative legal protection against violations of the right to trial within a reasonable time in the proceedings before the Administrative Court of the Republic of Croatia is exhaustively observed, while special attention is paid to the practice of the European Court of Human Rights. Models of application of the European Convention for the Protection of Human Rights and Fundamental Freedoms are examined in administrative cases with a special reference to unreasonably long periods of resolving of the legal proceedings. In order to understand entirely the legal protection of citizens against violations of the right to trial within a reasonable time, in the proceedings in front of the Administrative Court of the Republic of Croatia, the paper describes the development of the institute of legal protection to prevent the administrative silence in Croatia. As a result of Croatia gaining full membership to the European Union, significant changes have occurred in terms of much-needed cooperation between national administrative courts and the European Court of Human Rights, in order to avoid contradictory court practice for the same legal issue, or for the same case.