Hantavirus disease are zoonotic infections and remain a clinical challenge with globally increasing incidence and multiple serious outbreak situations in Europe within the last years. Hantavirus disease encompasses two clinical syndromes, hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS) caused by Old World and New World hantaviruses, respectively. Depending on the causative Old World hantavirus species, clinical course of HFRS can vary from mild to moderate to severe. At present, there is no specific therapy available for hantavirus disease. As the clinical course of hantavirus disease is dependent on the causing viral pathogen and as there worrisome hints that clinical course HFRS and HCPS overlap, further studies with regard to the disease course are mandatory. Furthermore, the examination of attributable mortality and costs of hantavirus disease will need to be studied on a multinational basis and therefore HantaReg will particularly use a matched case control design.