Subject of research: institutions under transitional economc system. Objective of the research: disclosure of the role of informal institutions in the transitional economy. Methods of research: induction and deduction, generalization, analysis and synthesis, abstracting, causal analysis. Results, novelty: 1) it is shown that institutes can influence on transactional costs in a direction of reduction the quantity of the information and time, necessary for decision-making, so in a direction of their increase, 2) informal institutes are defined as mechanisms which adjust behaviour of people by means of the certain stereotypes, standards and the social reserves which are not certain legislative and statutory acts, 3) alongside with traditions and customs, to informal economic institutes are ascribed social reserves as external rules which influence behaviour of managing subjects during short time, 4) ways of interaction of formal and informal institutes are systematized: updating (change of informal institutes under influence of formal, and on the contrary, change of formal institutes under influence of informal), formalization (legitimization of informal institutes to formal), deformalization (transformation of formal institutes into informal), 5) features of evolutionary institutional changes on the post Soviet space are shown, 6) the important condition of effective adaptation of imported institutes is grounded - principle of integrated approach and character, which means importation of set of interrelated (complementary) institutes, sufficient for realization demanded institutional changes, 7) directions of the state influence on informal institutes in transitive economy and means corresponding them are systematized, 8) classification of types of import of institutes is supplemented by inclusion of import from the history of other countries and developing a technique of an estimation of efficiency of import of the institutes, which stands for an estimation of benefits and costs of importation and their comparison. Sphere of usage: Teaching of the Economic theory, Institutional economy, Neoinstitutional economy, practice of market transformations management.
