The article is devoted to the problems and perspectives of the theory of separation of powers. The general aspects of the theory of separation of powers are outlined. The authors say that the multiplicity of types of power and types of social norms and factors, that ensure them, shows that separation is inherent to the phenomenon of power. It was noted that the issue of separation of powers has an important theoretical and practical significance and is closely related to the classification of political regimes into totalitarian, authoritarian, democratic and liberal. It was emphasized that, contrary to the established stereotype, the separation of powers, in certain forms, existed long before the epoch of Ch.L. de Montesquieu. It is noted that the ideas of separation of powers long before J. Locke and Ch.L. de Montesquieu was also expressed by Aristotle and Marsilius of Padua. It was substantiated that, in fact, the separation of powers has existed in some forms since the very beginnings of statehood. So, the theory of the separation of powers does not arise, but is only actualized in the XVII-XVIII centuries in connection with the struggle of the bourgeoisie against absolutism and feudal-clerical orders. It was noted that existence of the separation of powers for a long time before the period of the bourgeois society says that the separation of powers, as such, does not protect society from slavery and serfdom, arbitrariness and tyranny, inquisition and oppression, but, on the contrary, can increase the number of tyrants, independent of each other. The authors say that the separation of powers into the legislative, executive and judicial branches does not protect society from tyranny and usurpation of power by one party, while the incompleteness of the separation of powers (in particular, in the countries of the Anglo-Saxon legal family) does not turn the state into a tyranny. The authors pay attention to the critical view on the separation of powers in the works of J. Bodin, T. Hobbes, G.F. Szerszeniewicz, who say that the real separation of powers is dangerous to the unity of the state. It was emphasized that the theory of separation of powers contradicts the basic characteristics of the state sovereignty, defined by J. Bodin, because if the power is limited and separated into several branches, then it cannot be unified, supreme, absolute and permanent. The historical experience of different riots, rebellions and civil wars, that confirms the validity of the mentioned concerns, was provided. It was noted that the separation of powers in the state can have only a functional nature. It was noted that excessive separation of powers can paralyze state management or significantly complicate the system of state authorities and intensify the struggle between them, which will contribute to the establishment of a dictatorship. The authors support the position of G.F. Szerszeniewicz that the «legal self-limitation of the state» is a fiction and indicate that, theoretically, the limitation of the state by law is most likely in the states of the Anglo-Saxon, religious or traditional legal family, where the legislation, created by the state, is not the main source of law. Following B. Constant, it was stated that, in fact, the number of branches of power in the state is much greater than 3, and it was noted that, in particular, in modern Ukraine, we can talk about 9 branches of government, which creates the need to rethink the classical postulates of the theory of the separation of powers and the mechanism of checks and balances, as well as the necessity of expansion and addition of the typology of political regimes, etc.