This master's thesis consists of a theoretical part where the concepts of entrepreneurship and startup companies are explained, while the empirical part examines the impact of the internal environment, microenvironment and macroenvironment on the success of startups. There are numerous definitions of entrepreneurship, but the most complete is that of Wennekers and Thurik who define entrepreneurship as “the obvious ability and willingness of individuals, themselves, in teams, inside and outside organizations, to see and create new economic opportunities and to bring their ideas to market, facing uncertainty and other obstacles. The term startup does not have a unique definition, but the given definitions can be synthesized and from that characterize a startup as an entrepreneurial venture that is typically a new, fastgrowing business and aims to meet market needs by developing an innovative product, process or service. The importance of entrepreneurship for economic growth has been unquestionable for a long time, but in recent times more and more attention has been paid to the impact of startups on economic growth and development, which is just as enormous as in entrepreneurship. The aim of the research was to examine which of the three dimensions of the environment most influences the success of startups. Primary data were collected using an online survey questionnaire and analyzed descriptively and by implementing the Friedman test, Wilcoxon test and correlation. The results showed that the internal environment has the greatest impact on success, followed by the microenvironment and finally the macroenvironment. The contribution of research is reflected in the identification of the impact of the environment on success, with the consequence of increasing the percentage of successful startups. Limitations of the research are present in the form of sample size (N = 61) and subjective assessment of the success of the respondents. Recommendations for future research include repeating the research on a larger sample, covering the international level, and comparing the results at the international level.