European Reference Networks (ERNs) are virtual networks involving healthcare providers across Europe. They aim to tackle complex or rare diseases and conditions that require highly specialised treatment and concentration of knowledge and resources. No country alone has the knowledge and capacity to treat all rare and complex diseases. ERNs offer the potential to give patients and doctors across Europe access to the best expertise and timely exchange of life-saving knowledge, without having to travel to another country. The mission of ERN GUARD-Heart is to facilitate access to diagnosis and treatment of rare and complex diseases of the heart in adult and paediatric patients across the European Union. ERN GUARD-Heart brings together 24 expert healthcare providers from 12 different Member States committed to patient-centred care and efficient practice based on evidence, knowledge, education, and translational research. The focus is on genetically transmitted heart disease and several specific procedures in paediatric patients.