The European Clinical Research Infrastructure Network (ECRIN) is a sustainable, non-profit, distributed infrastructure whose mission is to support clinical research in Europe, and in particular multinational clinical studies. ECRIN assists academic investigators and sponsors, as well as SMEs, to overcome the obstacles associated with multinational studies in Europe. Multi-country studies provide increased access to patients, resources, and expertise, and, in turn, potentially more robust study results and a greater public health impact. Difficulties in coordinating clinical trial units, fulfilling local legal, regulatory and ethical requirements, and coordinating multinational study management deter many researchers from attempting multinational trials and studies. This means that most independent studies are conducted in a single centre, or multiple centres within one country. ECRIN provides a pathway through Europe’s fragmented health and legal systems with its pan-European infrastructure that is designed to support multinational clinical research and unlock the European clinical research capacity. ECRIN started in 2004 by connecting research facilities at multiple sites in countries across Europe and providing services for top-level clinical research. It was officially awarded the status of European Research Infrastructure Consortium (ERIC) in November 2013 it has undergone an independent scientific evaluation in 2019 and the first round of ESFRI monitoring in 2023. ECRIN works to fulfil its vision to generate scientific evidence to optimize medical practice by accompanying the different actors from advice and preparation, through to the setup, and management of a multinational study. Its expertise is disease agnostic and can be applied in any field (see services section). ECRIN’s organisational model is based on country membership. ECRIN currently has 13 Member and Observer countries (Czech Republic, France, Germany, Greece, Hungary, Ireland, Italy, Norway, Poland, Portugal, Spain, Slovakia, and Switzerland) covering 361M citizens and more than 80% of the European population. Each Member and Observer country hosts a European Correspondent (EuCo). EuCos are national ECRIN staff, who are clinical research experts with extensive knowledge of the national and European clinical research landscape. Together they coordinate the clinical study portfolio and work closely with the national scientific partners (i.e. a network of clinical trial units, CTUs) and with their colleagues based at the Paris headquarters. ECRIN’s national partners unite over 130 CTUs all providing high-quality support and services for clinical research from study planning to preparation of the final report. The CTUs work in a broad range of medical fields, and some have specific expertise, for example, in paediatrics and vaccines. They can cover clinical studies for the development of new drugs, medical devices, or therapeutic strategies, as well as repurposing or comparative effectiveness. These CTUs, all ECRIN partners, are selected for a given study based on their resources and areas of expertise. They have also demonstrated their compliance with ECRIN quality standards. Currently, ECRIN’s clinical trial portfolio counts over 75 multinational studies with an average of 6.5 countries per clinical study.