One year on from their launch, ERNs are treating more than 50 patients with rare diseases. Such is the nature of rare and complex diseases, that specialist knowledge is scarce and fragmented, and therefore often unavailable in the patient’s region or country. Case studies are used in this article by Vytenis Andriukaitis, European Commissioner for Health and Food Safety to demonstrate how this makes ERN work on rare diseases an area of enormous EU-added value; using the EU’s great pool of knowledge and expertise and by connecting our assets through ERNs can bring concrete benefits to many thousands of patients.