Energy policies of Slovakia and the EU from the aspect of sustainability and regional development and their impact on the Horná Nitra region Energy systems are undergoing a deep transition, which influences the whole economy and society. Energy policies and other strategy documents should define goals, implementation steps and measures for the transition of energy systems on a national and European level. The aim of this article is to analyze, evaluate and compare the currently valid documents: the energy policy of the Slovakia from 2014 and the package of documents and measures "Clean Energy for All Europeans" (2016), which defines the recent energy policy of the EU from the aspects of sustainable development (SD) of energy systems and regions. The basic criteria of SD of energy system were defined. The strategic goals, priorities, legislative proposals and measures of both policies were evaluated as positive, negative or ambivalent in relation to the defined criteria. The Horná Nitra region was taken as an example of a coal region in transition to show the influence of an energy policy on this process. The conclusion shows that the carent energy policy of the Slovak Republic does not support the SD of energy system and regions and many of its goals and measures contradict the energy package of the EU, which supports and promotes them. The elaboration and approval of a new energy policy of the Slovakia is therefore inevitable.