The decline of the democratic wave which has been manifested in the de-liberalization of the larger part of “new democracies” constitutes one of the most important trends in the global political processes in the first decade of the XXI century. Meanwhile the practice of democratic transition demonstrates that political institutional structure and an electoral system as its key element may acquire great significance in the consolidation of democracy. From the point of view of political theory, the consolidation of “new democracies” can be preferably accomplished with the help of electoral systems based on the principle of proportional representation. This type of electoral systems promotes the development of political parties, contributes to the representative form of government and encourages the growth of civil political culture and feelings of national unity. As far as electoral systems based on the principle of majority representation are concerned they, on the contrary, cumber the representation of the interests of minorities and weeken the national identity. The realities of the democratic transition in post-communist countries of Europe and Eurasia confirms the author’s hypothesis about the significance of the type of electoral systems and its impact on the dynamics of consolidation of “new democracies. There exists a meaningful positive correlation between, firstly, forming a parliament with the use of the proportional representative system with party poll lists and stable democratization; secondly, between the mixed system and unstable democratization; and thirdly, between the majority two-round system and failed democratization. The above noted correlations point to the fact that the success of consolidation of “new democracies” is mostly dependent on the force of the parliament which has the power to control and restraint the executive branch. The comparative analysis of democratization processes in post-communist countries makes clear an apparent tendency towards increasing the political influence of parliaments in proportion with more widely use of the principle of proportional representation during nation-wide elections to legislature. Nevertheless, the significance of the type of electoral systems which defines the results of transition to democracy should be acknowledged to be limited. Moreover, the choice of the type of an electoral system and hence the degree of its impact on the process of consolidation of “new democracies” have always been the reflection of political culture specifics in the countries that have taken the course of democratization.