Peculiarities of regional processes of foreign direct investment impact on the gross domestic product of Western Ukraine and Chernivtsi region, taking into account a time lag, are reviewed in this article. Considering the fact that investment processes are enough complicated phenomenon to understand in the course of which different kinds of changes occur, the relevance and importance of establishing a pattern of their behavior is increasing. Economical and mathematical tools, in particular Almon distributed lag models which allow to estimate the discrete lag influence of determinants can be used to achieve this. In the course of the study, the Almon distributed lag models were constructed separately for the comparison, time lag interval boundaries were set, the main features of the discrete time lag distribution during the lag period were determined, and the economic and mathematical models of the distributed lag for the effects of foreign direct investment on the gross regional product of Chernivtsi region Western Ukraine were built. On the basis of the obtained results, conclusions about economic multiplier processes of the investment were made in the context of individual territories and the main trends of the investment flow return were defined.