Patients with highly infectious diseases require safe, secure, high-quality medical care with high-level infection control, which may be most effectively delivered by specially trained staff in the setting of a high-level isolation unit (HLIU). The European Network of Infectious Diseases is a European Commission co-funded network of experts in the management of highly infectious diseases from national (or regional) centres designated for the care of this patient population. Participants took a consensus-based approach to develop a framework for the design and operation of HLIUs in Europe, covering clinical care provision, diagnostic services, transport, health and safety, and essential design and construction features, to support planning by health authorities for the safe and effective management of highly infectious diseases and preparedness for infectious disease emergencies in Europe.