SUMMARY
It has been substantiated that the use of a research strategy of rational choice institutionalism was one of the factors that contributed to a return to the institutional theory of policy analysis individual dimension in the paper. Possibilities to achieve utility and distribution of resources in society at the political process micro-level began to be considered as sufficiently important resultants of functioning of the institutional system alongside macro-politics. In addition, it is specified that application of the methodology of the STEM subjects has allowed characterizing the activities of political institutions using the terms of effectiveness, which led to a reorientation of the study of their informal varieties as real regulators of political behaviour. However, the interest in empirical development has created the danger of rationalizing the politics up to its dehumanization, whereof avoiding, according to foreign political scientists, is possible adhering to ethical constraints that arise from the peculiarities of complex human nature.As a result of the analysis held, it has been found that, unlike the studies of foreign experts who distinguish various substantive areas of analysis in the theory of rational choice institutionalism, the applied potential of implementation of elements of its methodology in the works of Ukrainian scientists is rather instrumental. The general conclusion is that the research strategy of this version of new institutionalism in the practical plane is used mainly as one of many methodological approaches to the study of different political phenomena and processes. To some extent, similar to the particular area of research that reveals the analytical resource of rational choice institutionalism is to study the peculiarities of formation and functioning of parliament and the related processes (electoral strategies and coalition arrangements).It is emphasized that the most interesting for us may be the segment of scientific works, which are based on the theory of rational choice institutionalism, and related to the analysis of those factors that may impede democratic transformations in transitional political systems. It can be argued that inefficient political institutions, despite their irrational nature, continue to function in the political system because they are the product of a rational choice of influential political actors. In this case, the understanding of the very concept of rationality is distorted, which from an absolute category is transformed into a relative one, not only because of the limitations associated with the action of moral and ethical factors, but mainly due to maintenance of an inefficient institutional equilibrium, i.e. an institutional trap.