This masters thesis should give a comparative overview of the supreme audit institutions of three selected European Union member states: Croatia, Czech and Germany. The period that was observed in this thesis is the financial year 2013, because this is the year that Croatia entered the European Union as a full member state. The comparison with a highly developed member state (Germany) and comparison with a state that is similar in development to Croatia (Czech) is considered interesting for the purpose of writing this thesis. Similarities and differences starting from the organization of the supreme audit institutions, legal framework that governs their work, the way that audit is conducted, historical comparison, planning and methods, along with reports issued for FY 2013 from the institutions are being shown in this master thesis. The literature used in the thesis is accessible online, due to the fact that each of the observed institutions has to publicly issue their reports, plans and activities, and they have a legal obligation for transparency to the public. Most of the data acquired for the purpose of writing this thesis is publicly accessible through issued reports and various legal acts. The conclusions, similarities and differences in the framework, organization and findings of the observed supreme audit institutions of Croatia, Czech and Germany are summarized in the Conclusion of the paper.