The objective of this thesis is a comprehensive analysis of legal aspects of obtainment of construction and operating licences in the Republic of Croatia. The fundamental research focus of the thesis is aimed at an analysis of deficiencies in performance of administrative procedures concerning obtainment construction and operating licences where the determined deficiencies may lead to inefficiency of these special administrative procedures. The subject of this paper concerns application of construction regulations at the level of the European Union, the position and the rank of the Republic of Croatia in comparison to the European Union Member States in respect of the construction administrative law regulatory systems, and the origin and consequences of the determined deficiencies in the administrative procedure concerning obtainment of the construction and operating licences in the Republic of Croatia. Research hypotheses were set on the basis of the defined objective, the problem and the subject of research proven through studies and analyses of primary publications and general normative acts (of the Republic of Croatia, of the European Union Member States, and of the European Union), case-law (of the European Court of Justice, the European Court of Human Rights, administrative courts, the High Administrative Court of the Republic of Croatia and the Constitutional Court of the Republic of Croatia), research performed by the World Bank and the OTB Research Institute for the Built Environment, Delft, the Netherlands, and performed empirical research. Research survey polls were performed on two groups of subjects. The first group consisted of architects, members of the Croatian Chamber of Architects, and the second group consisted of heads and/or employees of competent county and city level administrative departments of the local and regional self-government units (including their subordinated offices) which issue construction and service licences. Poll responses were subjected to various types of qualitative, quantitative and causal analyses and syntheses. The data was analysed using descriptive statistics and the differences between the responses provided by the two groups of subjects were analysed using appropriate statistical tests. Other methods applied in order to prove the established hypotheses were: analysis and synthesis, induction and deduction, abstraction and specification, the comparative method, the historical method, the method of description, the method of compilation, the method of observation, and, in the course of the analysis of the legal regulations, grammatical, logical and teleological methods of interpretation were used. Using the research methods, it was determined that more efficient construction law regulatory systems may be identified in the European Union Member States. Furthermore, considering the group of surveyed heads and employees of competent county and city administrative departments (also including their branch offices), it is not clear or fully determined that development of administrative construction law in the Republic of Croatia has not led to simplification of procedures for obtainment of construction and operating licences, but the same was confirmed in relation to the group of surveyed architects. By application of the research methods, it was also determined that the procedures for obtainment of construction and operating licences in the Republic of Croatia have not been fully aligned with provisions of the General Administrative Procedures Act and the sources of law regulating the administrative procedure at the EU level. Accordingly, deficiencies of the administrative procedures, leading towards inefficiency of such special administrative procedures, have been determined. Considering the determined circumstances, the Conclusion of the paper provides recommendations for improvements concerning proposed normative improvements de lege ferenda and institutional and/or organisational improvements of the system.