This dissertation analyzes, in the period 2005-2019. in Croatia and Slovenia, the development of entrepreneurial infrastructure and its correlation with indicators of socio-economic development. For the same, it was necessary to determine and define the key infrastructure that has an impact on socio-economic development and, considering the created historical context of it, it was concluded that with regard to various forms, the greatest impact on the socio economic development of these two countries is of the entrepreneurial zones, business incubators and development agencies. In order to get a more objective picture of socio economic conditions, a comparative analysis of the economic and social development of Croatia and Slovenia after independence and exit from the former state in 1991, as well as the transition of the social and economic system of both countries, was carried out. In the comparative presentation of the development of entrepreneurial infrastructure, the common characteristics and differences in the process of developing the entrepreneurial infrastructure of both countries were synthesized and specific and common characteristics were determined in positive and successful activities and results, but also in difficulties and negative reflections over time in encouraging the development of entrepreneurship, with the help of identified key variables of the business infrastructure. The entrepreneurial ecosystem is also viewed in the context of economic and social development, along with drivers of entrepreneurial productivity and European development strategies. Quantitative research described and interpreted the observed variables: the movement of the number of entrepreneurial zones, entrepreneurial incubators, development agencies and gross domestic product (GDP) according to market prices and employment for both countries, namely the values of the variables chain index and the arithmetic and geometric mean of the growth rate, while the hypothesis and auxiliary hypotheses were tested by regression analysis and conclusions were drawn. In summary, the absolute existence of correlation between all key variables of entrepreneurial infrastructure and employment and GDP according to market prices was confirmed in Croatia, while this is not the case for Slovenia and the correlation is evident only in the case of hypothesis H2, i.e. between all three key variables of entrepreneurial infrastructure and of GDP according to market prices.