In drug repurposing phase I trials on safety and tolerability may be considered or claimed for scientific reasons or by competent authorities. These may not have been part of the original study plan, particularly in investigator-initiated trial projects, causing unforeseen costs. One objective of the REPO4EU drug repurposing platform is to identify, ideally academic, phase I clinical trial sites that can provide comprehensive services from a first idea to the study plan, regulatory approval, sponsor role, operative conduct, monitoring to the final study report, and are willing to be listed as fee-for-service partners in the platform’s database. An exhaustive research including different sources was performed to identify academic phase I trial sites all over Europe with different characteristics. Subsequently, the sites sites were contacted, asked to be part of the phase I network, and provided information on their capabilities. So far, 37 sites have self-registered for later publication on the Repo4EU platform, enabling direct matchmaking between researchers and phase I trial sites. The current database structure for phase I trial sites considers information on expertise and offerings, access to volunteers (or patients), and infrastructure relevant to filter and identify the most suitable partner for a specific project. In addition the REPO4EU platform will provide comprehensive information on phase I drug repurposing trials and a decision tree to check whether a phase I trial is required for a drug repurposing project linked to phase II information. With these resources REPO4EU provides a unique phase I information platform for drug repurposing projects. We expect the phase I network to grow continuously by registering additional sites, including outside Europe (registration link: https://ec.europa.eu/eusurvey/runner/REPO4EUClinicalSites)