EU aid funds enabled the municipalities to the realization of costly infrastructure investments to raise the standard of living, and hence their competitiveness. Implemented investments affect the socio-economic development, which is particularly evident in case of rural communities. It follows that EU assistance funds are an instrument of development policy, both in the regional and local levels. They will lead to a widening of the investment potential of the development of municipalities. Municipalities with different activity and effectiveness reach for the EU funds. Hence the purpose of this article is to attempt to find a relationship between the amount collected financial support for infrastructure investment and the level of socio-economic development of municipalities. The study included five rural municipalities located in three regions of Polish statistics (NUTS 1) - the northern, north-western and eastern. The analysis based on literature query, and using simple statistical methods. The study was conducted in several stages in the analysis of investment projects co-financed from EU funds, as well as the indicator showing synthetically socio-economic conditions of communities. The analysis of the relationship between the levels obtained the support of the EU and the socio-economic development was carried out using the Pearson correlation index.