The aim was to study distinctive features of immune status in patients with acute and chronic diffuse myocarditis. We examined 67 patients, divided into 2 groups: 32 with acute diffuse myocarditis and 35 with
chronic diffuse myocarditis. Control group included 20 healthy people. In both groups of patients with myocarditis we observed activation of immunopathologic reactions with autoimmuneinduced cardiac damage. The most significant activation of the immune system and impairment of left ventricular systolic function, as its sequence, was found in the group of patients with acute diffuse myocarditis. The most important markers of myocardial damage in myocarditis are cardiac autoantibodies and their titers, Creactive protein, tumor necrosis factor alfa and interferon gamma.