In recent years, the definition of cardiomyopathy has been restricted to the idiopathic forms of myocardial disease and has been grouped into three general categories: (1) congestive or dilated cardiomyopathy, (2) hypertrophic cardiomyopathy, and (3) restrictive cardiomyopathy. The history and physical examination and echocardiography appear to be the most helpful in the clinical recognition of these disorders. In general, the prognosis of patients with congestive cardiomyopathy is guarded. Their survival primarily depends on the natural history and progression of the disease as well as the response to treatment with anticongestive drugs. The recent advent of vasodilator therapy has provided additional help to the patient with refractory congestive heart failure. Hypertrophic cardiomyopathy appears to be much more frequently recognized since the advent of echocardiography. The young patient has a much higher incidence of serious complications (combined right and left ventricular outflow obstruction, more generalized hypertrophic cardiomyopathy, and sudden death), and the patient presenting in later life appears to have fewer associated complications. There is a familial association with hypertrophic cardiomyopathy, although the true incidence and full expression of the association is not well understood at present. The majority of adult patients acieve prolonged survival with medical and/or surgical treatment. The restrictive cardiomyopathies are probably the least well understood. All three subgroups (Löffler's endocarditis, primary restrictive cardiomyopathy, and endomyocardial fibrosis) have a guarded prognosis. The acute form (Löffler's endocarditis) is characterized by a debilitating illness with death usually within a couple of months; however, a small percentage of these patients can have long survival and may actually evolve into a more chronic form, i.e., primary restrictive cardiomyopathy or endomyocardial fibrosis. The latter two restrictive myopathies usually have a slow indolent course, and their prognosis is primarily determined by the amount of myocardial damage and endocardial fibrosis.