Successful development of the Ukrainian economy, its agro-industrial segment requires a large-scale and efficient investment provision and favourable investment climate. In this regard, the actual task of the scientific community is the study of the influence of institutions on the development of investment policy, the formation of investment processes in the country. The purpose of this article is the study of institutional basis for further development of the investment processes in the agricultural sector of Ukrainian economy under conditions of integration into Europe. In the study process author used general scientific methods, in particular statistical method, method of extrapolation, analogy, institutional analysis, abstract-logical method, methods of descriptive simulation. Results of the study are as follows. The influence of formal institutions (legal regulations for the ‘rules of play’) was assessed on the investment efficiency. The ponderability of the formal institutions was identified in the investment success of the big agricultural business of Ukraine. The main causes of the low investment attractiveness of small and medium-sized business in the agrarian sector of the Ukrainian economy were defined. The ways were substantiated for development of the non-formal institutions. It was accentuated that asset capitalization of the small and medium-sized companies would be important for development of the investment processes in Ukraine.