EXECUTIVE SUMMARY The Electricity and Gas Directives issued by the European Commission have set the objective of integrating the regional Member States into a single market, in order to ensure energy efficiency, security of supply and competitiveness. Greece has been driving efforts for liberalizing its national electricity and gas markets, opening them to competition. Although since July 2007, officially all eligible customers can choose their electricity supplier, the actual market opening is limited. The natural gas sector is an emergent market, and the focus is on developing the infrastructure and facilitating its penetration in the urban regions, before even considering real liberalization. The objective of this study is to indicate the factors that influence the restructuring of Greece’s energy markets and its market structure. By examining the way which the EU’s Directives are implemented in the country’s legislation, assessing the obstacles that impede competition and addressing security of supply issues, the strong points and the challenges of the domestic energy markets are presented. For the research question to be answered, the initial conceptual model is formed, based on literature review and European Commission and national documents. Subsequently, data is collected from interviews with the key players of the Greek energy setting, mainly with the incumbent companies, the operators of the networks and the regulatory authorities. The additional drivers that impact the status quo of the electricity and natural gas markets through the eyes of the interviewees shape the advanced conceptual model. After analyzing and comparing the findings, the paper concludes that the deregulation of the conventional energy markets lags behind. The domestic markets remain rigidly national, with energy monopolies and limited new participants.