The article provides a comparative analysis of the republican system of Estonia and Finland, each of which has certain historical parallels with Ukraine (Finland was part of the Russian Empire during the 19th-early 20th centuries, Estonia was part of the USSR in the 40-80s of the 20th century). It is emphasized that the established experience of solving the problem of stabilization of the domestic and foreign political situation defined by the constitutions of the countries is successful, Finland and Estonia are members of NATO and the EU, therefore there is an opportunity to use their experience in Ukraine. The principles of the organization and functioning of the state bodies of the specified states, the rights and duties of citizens, the peculiarities of the activity of the parliament, the peculiarities of the exercise of executive power, the powers of the country's presidents, the peculiarities of their election and legal status are considered. It is concluded that there are structural and substantive similarities and differences between the republican system of Estonia and Finland. It is shown that such features include the unitary nature of states, a fairly broad list of rights and freedoms of citizens, the provision of the principle of habeas corpus, the appointment of Prime Ministers and ministers by parliaments, the exercise of executive power by governments, the accountability of governments to legislative bodies, the election of the Presidents of both republics for only two terms «consecutive» terms. It is outlined that the differences include different ways of electing Presidents (in Finland ‒ by parliament, in Estonia ‒ by direct elections); different terms of office of presidents (the President of Finland for 6 years, the President of Estonia for 5 years); differences in the form of government (parliamentary republic in Estonia and mixed semipresidential republic in Finland); different number of state languages: one (Estonian) state language in Estonia and two (Finnish and Swedish) in Finland; granting the President of Estonia the status of head of state by the Constitution and the absence of such status in the Basic Law of Finland; exercise of executive power in Finland by the President of the Republic together with the State Council, in Estonia ‒ only by the Prime Minister and ministers. It is emphasized that Estonia and Finland differ in solving the problem of citizenship and the rights of national minorities. Finnish autonomy is not just a special status, but a mini-constitution of the islands, under which a system of counterbalances of state and local (autonomous) interests operates, which is not typical for Estonia. [ABSTRACT FROM AUTHOR]