Dilated cardiomyopathy (DCM) is a myocardial disease characterized by progressive depression of myocardial contractile function and by ventricular dilatation. Abnormalities of the cellular and humoral immune system are present in patients with myocarditis and DCM. Various circulating cardiac autoantibodies have been detected among patients suffering from DCM. The relative contribution of cardiac antibodies to cardiac malfunction in DCM remains to be elucidated. Extraction of antibodies by immunoadsorption has been successfully used for treatment of various autoimmune diseases. In this review we report recent studies, which indicate that immunoadsorption improves cardiac function of patients with DCM. The data from these studies indicate that activation of the humoral immune system, with production of cardiac autoantibodies, may play a functional role in cardiac malfunction of patients with DCM.