Cardiomyopathies are a heterogeneous group of diseases with structural and functional myocardial abnormalities. Primary cardiomyopathies are those that predominantly affect the myocardium. Common examples are defects in contractile proteins such as myosin binding protein C and myosin heavy chain. Secondary cardiomyopathies are myocardial disorders that develop in addition to multiorgan involvement. These include glycogen storage diseases and mitochondrial disorders. Recent advances in molecular genetics, proteomics, physiology and cellular biology, as well as imaging and clinical care have led to improvements in knowledge about the etiology, mechanism and treatment. The most impressive discoveries concern the genetic basis for many cardiomyopathies, which has led to remarkable diagnostic advances, and novel targeted treatments including enzyme replacement therapy. Our knowledge of the role of mitochondria in disease has rapidly increased. Cardiovascular complications remain dominant clinical concern in most patients with metabolic cardiomyopathies but advances in care are leading to improved survival.