Despite recent advances in the management of patients with heart failure, morbidity and mortality rates remain high. Common causes of heart failure are ischaemic heart disease, uncontrolled hypertension and valvular disease. However, in up to 50 % of the cases its exact cause remains initially unknown; this condition is called idiopathic dilated cardiomyopathy (DCM). Improved diagnostic methods, most notably the advancements in molecular and immunohistological biopsy techniques and genetic research, have endorsed a new era in the diagnosis and classification of patients with idiopathic DCM. These insights have led to novel aetiology-based treatment strategies and improved outcome. The present article will briefly discuss all causes of DCM with a special focus on inflammatory- and virus-mediated forms of DCM.