Acute myocarditis is one of the most challenging diagnosis in cardiology. At present, no diagnostic gold standard is generally accepted, due to the insensitivity of traditional diagnostic tests. This leads to the need for new diagnostic approaches, which resulted in the emergence of new molecular tests and a more detailed immunohistochemical analysis of endomyocardial biopsies. Recent findings using these new diagnostic tests resulted in increased interest in inflammatory cardiomyopathies and a better understanding of its pathophysiology, the recognition in overlap of virus-mediated damage, inflammation, and autoimmune dysregulation. Novel results also pointed towards a broader spectrum of viral genomes responsible for acute myocarditis, indicating a shift of enterovirus and adenovirus to parvovirus B19 and human herpes virus 6. The present review proposes a general diagnostic approach, focuses on the viral aetiology and associated autoimmune processes, and reviews treatment options for patients with acute viral myocarditis.