Abstract Purpose This paper aims to address which resources provided by an entrepreneurial ecosystem (EE) are necessary for deep technology entrepreneurship. Design/methodology/approach The authors used a novel approach known as necessary condition analysis (NCA) to data on EEs and deep-tech startups from 132 countries, collected in a global innovation index and Crunchbase data sets. The NCA makes it possible to identify whether an EEs resource is a necessary condition that enables entrepreneurship. Findings Necessary conditions are related to political and business environment; education, research and development; general infrastructure; credit; trade; diversification and market size; and knowledge absorption capacity. Research limitations/implications The results show that business and political environments are the most necessary conditions to drive deep-tech entrepreneurship. Practical implications Policymakers could prioritize conditions that maximize entrepreneurial output levels rather than focusing on less necessary elements. Social implications Some resources require less performance than others. So, policymakers should consider allocating policy efforts to strengthen resources that maximize output levels. Originality/value Studies on deep-tech entrepreneurship are scarce. This study provides a bottleneck analysis that can guide the formulation of policies to support deep-tech entrepreneurship, as it allows to identify priority areas for resource allocation.