The Republic of Bulgaria has been a member of the European Union since 2004. Due to this fact, for more than a decade intensive work has been carried out to modernize Bulgarian energy sector. In 2011, the program called “Energy Strategy of the Republic of Bulgaria till 2020 for reliable, efficient and cleaner energy.” This strategy is a basic document regulating the national energy policy, whose principles have been adapted to the energy policy of the European Union. Bulgaria’s energy policy is largely determined by the volume of the country’s own energy resources, which, unfortunately, are insufficient for the growing needs. It is also significantly influenced by renewable energy sources and projects of its use. One should bear in mind that the geopolitical situation of Bulgaria promotes diversification of strategic raw material sources, which is confirmed by planned and ongoing investments. In this respect, it is worth noting a still significant dependence on Russia. Foreign investors’ interest in Bulgaria is also growing, especially from the point of view of the distribution of oil and natural gas from Russia or Central Asia to Europe. The article presents an analysis of the energy sector of Bulgaria together with the country’s energy strategy until 2020. Energy resources are described by specifying the non-renewable (like oil, natural gas, coal) and renewable energy sources (such as hydro, geothermal, solar and wind energy as well as biomass). Also, the article includes an outline of the issues which are key to the energy sector of Bulgaria, i.e. the level of electricity production and the scope of production and import of oil and natural gas. What is more, the most important objectives of the energy strategy of the Republic of Bulgaria for the period up to the year 2020 have been presented in this work. Another aspect that the paper describes are the most important Bulgarian investments in the energy sector, including those that are already being implemented and the ones that are planned to be introduced (Nabucco, South Stream, AMBO oil pipeline, the Burgas-Alexandroupoli TBP oil pipeline). The concluding part of the article constitutes an attempt to assess the energy strategy of the Republic of Bulgaria.