ENThe process of organization and functionality of one of the most important attributes of any modern democratic legal state, i.e. the state power, is based on certain principles. The principle of separation of powers is universally acknowledged as such a fundamental principle, thus it is generally established in the constitutions of democratic states. Upon restoration of Independence the state power in the Republic of Lithuania is also implemented based on the doctrine of separation of powers. Particularly increased interest in this phenomenon was determined by transition to new grounds for organization of the state power in Lithuania since 11 March 1990. Furthermore, the relevance of this issue was also determined by the lack of clear enough regulation of the principle of separation of powers in the Constitution of Republic of Lithuania.The research starts with the topic of legal indetermination of the principle of separation of powers, brief review of the historical aspect (development) thereof as well as revelation of the essence and the meaning of this principle. The Article analyses which Article (Paragraph thereof) of the Constitution of Republic of Lithuania regulates the aforementioned principle based on the doctrine of the Constitutional Court of the Republic of Lithuania and work done by scholars of the constitutional law. In absence of clear differentiation of authorities implementing state power by branches in the Constitution, the necessity to determine the relation between the highest-ranking authorities implementing the state power (the Parliament (Lithuanian: Seimas)), the President of the Republic and the Government, Court) and the respective type of the state power becomes relevant. In general, the aim of this Article is to reveal the essence of the doctrine of separation of powers, to discuss regulation thereof by the fundamental state law of Lithuania, and to identify the state authorities representing certain branches of the state power. The conclusions of the conducted research are presented at the end of the Article. [From the publication]