Dilated cardiomyopathy is a form of heart disease characterized by ventricular dilatation and reduced systolic function. In most patients, dilated cardiomyopathy is a sporadic disease. However, 20% of dilated cardiomyopathy patients may have a familial form of the disease. The aetiologies of both the sporadic and familial forms of dilated cardiomyopathy are unknown in most cases. Dilated cardiomyopathy has a spectrum of clinical and subclinical presentations. During the last 10 years, there have been many investigations concerning the possible aetiologic role of immune factors in dilated cardiomyopathy. It is plausible that an antecedent viral infection initiates an immunological cascade which in turn leads to production of autoimmune antibodies resulting in dilated cardiomyopathy. However, in most dilated cardiomyopathy patients, an antecedent viral infection cannot be identified. Similarly, the trail of immunological research has diverged as different groups have identified distinct autoantibodies or other immune factors in heterogeneous subsets of dilated cardiomyopathy and control patients. In this manuscript, we review the studies which have contributed supportive and confounding evidence to the theoretical autoimmune basis of dilated cardiomyopathy.