The EuRRECa project, launched in 2018, includes e-REC (e-reporting for rare conditions) and is approved by the Science Committee of Internal Medicine at the Leiden University Medical Center, the Netherlands and the National Ethics Service and Information Governance authorities in the UK. Participating centres are advised to check if they require local approvals at their own centre. No identifiable or partially identifiable personal information is captured in e-REC and individual patient consent is not required. The reported data are stored on a secure server in the Leiden University Medical Center and all information provided is kept in compliance with the General Data Protection Regulation (GDPR 2016/679).