The startup ecosystem in the Czech Republic falls far below the level of the developed economies of its Western neighbours. The startup map of the Czech Republic shows 1717 continuously operating startups. And yet they have yet to receive priority attention in the academic realm. The primary goal of this article is to define the key factors of startup sustainability and to looks for dependencies between them. The secondary goal is to identify the weaknesses of the Czech startup environment. The scientific hypotheses formulated focus on demonstrating the dependencies of selected factors influencing the startup sustainability. These have been verified on the basis of evaluation of data obtained via primary qualitative and quantitative research. Its findings were compared with the data of secondary research and with the conclusions of the scientific studies of international authors. The data was processed using statistical apparat. Thanks to this research, the authors have identified in their conclusion factors of the remote, immediate, and interior environments that can influence startup sustainability. They have demonstrated a correlation between the level of strategic management and the quality of internal communications processes, between the capacities of startup management to manage relationships with customers (CRM) and to drive communications strategy, including brand support. In real practice, however, nine out of ten startups do not succeed. The reason is that their design fails to understand and address the needs of customers and lacks marketing and managed sales.