Conflict of Interest in public administration is a frequent and significant problem present, more or less, in all countries of the modern world. This is a problem faced not only by transitioning countries with weaker legal and political systems like Croatia, but also by developed democracies. According to the OECD, a conflict of interest is defined as "a conflict between the public duty and the private interest of a public official, in which they have interests specific to their private sphere that could inappropriately influence the fulfillment of their duties and responsibilities. The subject of this paper is the comparison of the legal framework for preventing conflicts of interest among public servants in Croatia and selected EU countries divided into two categories: old, developed member states with strong legal systems, and new "transition" member states. The aim of comparing these two very different groups of countries is to identify similarities and differences in the approach of resolving conflicts of interest in public administration. The first part of the paper provides a definition of a conflict of interest and its types. It lists the definitions of conflicts of interest from the most important international organizations that have had a significant influence on member states in introducing the concept of conflicts of interest into national legislations. The second part of the paper is dedicated to the analysis of the Croatian legal framework for preventing conflicts of interest in public administration. It provides an overview of relevant provisions of the Law on Civil Servants and the Code of Civil Servants. Additionally, it explains the roles and responsibilities of ethical bodies, including the Commissioner for Ethics, the Ethics Committee, and the Office for Ethics and Integrity, as well as the civil service courts. The third chapter of the thesis presents the regulatory framework for preventing conflicts of interest in developed member states: Germany, France, and the Netherlands. The fourth chapter addresses the regulation of conflicts of interest in new, post-communist member states of the EU: Slovenia, Poland, and Romania.