Between 10 and 20% of patients with histologically proven inflammatory disease of the heart muscle develop a chronic disorder after acute myocarditis which results in dilated cardiomyopathy with increasing cardiac insufficiency. Viral infections are a frequent cause of inflammatory heart muscle diseases and thus also responsible for myocardial damage in the initial phase. In the past, evidence for enterovirus, adenovirus, and cytomegalovirus was in the focus of attention. In the meantime, "new" cardiotropic pathogens such as parvovirus B19, Epstein-Barr virus, and human herpesvirus 6 have been detected in patients with dilated cardiomyopathy with and without inflammation. Their persistence in the myocardium correlates with a decline in pumping capability within 6 months. While the virus is still being eliminated, the second phase of the disease begins, which is characterized by autoimmune phenomena and often a cardiac inflammatory response which likewise correlates with a worsening prognosis. The transition to the third and final phase with development of dilated cardiomyopathy occurs gradually and can take years. The goal of every diagnostic and therapeutic intervention must be to eradicate the virus and eliminate the inflammatory response to prevent the disease from progressing to terminal cardiac insufficiency.