The Electricity and Gas Directives issued by the European Commission 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 considering real liberalization. The objective of this study is to indicate the factors that influence the restructuring of Greece''s energy markets. Data is collected from European Commission and national documents along with interviews with the key players of the Greek energy setting. 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.