Idiopathic dilated cardiomyopathy (DCM) is one of the leading causes of severe heart failure and the most common cause of heart transplantation due to its ventricular dilatations and contractile dysfuntions. Twenty percent of DCM is in the familiar form and the rest is sporadic. The clinical impact of DCM is far greater than its position in epidemiological terms. Despite recent improvements in therapy, both incidence and mortality are still very high. The main problem is its heterogeneous etiology. So far, three factors have been identified to be potentially important: enteroviral infection, immune mechanism and genetic factors. During the last 10 years there have been many investigations showing distinct autoantibodies or other immune factors in heterogeneous subsets of DCM which have contributed supportive and confounding evidence to the hypothesis that multiple autoimmune mechanisms are involved in DCM. Accumulated evidence hitherto demonstrated a variety of circulating autoantibodies in the sera of patients with DCM including antireceptor autoantibodies, myosin and ADP/ATP translocator protein, etc. Data available from both in-vitro and in-vivo studies of anti-receptor autoantibodies as well as from other autoantibodies and autoreactive lymphocytes demonstrated clearly that a subgroup of DCM is autoimmunity-mediated. This is understandable because DCM is heterogeneous, implying that different subgroups of DCM may have different pathogeneses. It may be practical in the future to separate "autoimmune cardiomyopathy" from other "idiopathic" DCM.