Title: Competition Protection in Network Industries Abstract: I provide description of relevant markets within electroenergy industry in European countries since after liberalization movements of the last 20 years the development of these markets open new issues in antimonopoly legislation to be passed and in antimonopoly practice to be solved. The key term of any antimonopoly issue is the relevant market. Hence, its definition as provided by case law of European Commission and European Courts is crucial for companies as well as regulators to understand in order to be able to pursue their activities. As I show, after 20 or so years, the countries of the EU at least in electroenergy area are no closer to the Single Market as they were at the beginning of 90s before liberalization of electricity markets began and there is no sign of improvement for year to come. This thesis provides an overview (the tools and analyses) that can be used to explore individual national relevant markets in the area of electroenergy business. For further research it is worth exploring detailed analysis of relationship between price development and degree of competition, phasing of market opening, protection of small consumers and RES support within individual national energy systems. Keywords: competition, competition law and...