Systemic inflammatory diseases represent a large group of rare diseases that may involve all organs and also the heart. The three layers of the heart can be affected and some manifestations such as pericarditis in systemic lupus erythematosus are rather well known, yet others are not known even for cardiologists. Modern sophisticated imaging techniques reveal cardiac abnormalities in most of these diseases and the reported frequency of cardiac involvement ranges widely depending upon the applied diagnostic methods and selection of patients. The clinical significance of these findings is not always established. However, better knowledge and awareness of cardiac involvement is necessary because it conveys a major risk for mortality in several of these rare diseases.