Echocardiography was used to compare the left ventricular function in 35 cases of congestive cardiomyopathy (COCM), 16 cases of obstructive and 28 cases of non-obstructive asymmetric septal hypertrophy, 43 cases of scleroderma heart disease, 21 cases of ischaemic cardiomyopathy (ICM), 2 cases of restrictive cardiomyopathy, and one case of cardiac amyloidosis. COCM was characterized by left ventricular dilatation, decreased contractility and signs of elevated end-diastolic pressure. In asymmetric septal hypertrophy there was a decreased distensibility of the obstructed left ventricle, both in early and end-diastole, but the pump function remained normal. In scleroderma and amyloid heart disease both the contractility and distensibility of the small, stiff heart were reduced. In restrictive cardiomyopathy the only abnormality was the impaired end-diastolic distensibility. Reduced contractility confined primarily to the interventricular septum and impaired early diastolic distensibility are the characteristic features distinguishing ischaemic cardiomyopathy from COCM. However, echocardiography is not suitable for individual differentiation of ICM and COCM. The COCM can be differentiated from left ventricular aneurysm by M-mode sector scanning technique.