Increase of energy efficiency remains as one of the major strategic objectives in Lithuania. Effective use of existing energy saving potential increases energy security and reduces emissions of greenhouse gas and other pollutants. In order to meet the growing energy demand and to reduce the negative impact of the energy sector on environment, increase of the role of renewable energy sources in the country's primary energy balance, as well as larger deployment of energy-efficient and smart technologies in all areas, including military structures, are required. When analysing energy security and energy efficiency, as the two interrelated aspects of the Lithuanian energy policy, assessment of the global energy trends in the world, the EU and neighbouring countries, expected developments in the modern technologies, as well as global aspirations to neutralize the threat of climate change was performed. The paper provides an overview of energy consumption trends in the European Union and Lithuania, energy policy in the NATO alliance, as well the current status of energy consumption in the Lithuanian National Defence System.Reference to this paper should be made as follows: Baublys, J.; Miškinis, V.; Konstantinavičiūtė, I.; Lekavičius, V. 2015. Energy efficiency as precondition of energy security, Journal of Security and Sustainability Issues 4(3): 197-208.