Cardiomyopathies are a major cause of mortality and morbidity and this spectrum of disorders tops the list of diseases leading to cardiac transplantation. While significant gains have been made during the past decade clinically, knowledge of the molecular aspects of these disorders has taken longer to advance. During the past 5 years, however, molecular genetic information on a variety of primary cardiomyopathies, such as familial hypertrophic cardiomyopathy and X-linked dilated cardiomyopathy, has been obtained. Other primary and secondary myocardial diseases are now under study with advances occurring more regularly. The purpose of this review is to outline the major advances thus far described for some primary and secondary cardiomyopathies, as well as detailing the slower progress seen for others.