To evaluate the relation between cardiac function and myocardial damage in patients with dilated cardiomyopathy (DCM), we compared echocardiographic parameters and histopathologic findings of the biopsied myocardium in 50 cases with DCM. As wall motion is much influenced by the increased afterload in cases with large ventricles, we generated a new contractile parameter, Force-Velocity Product (FVP). FVP was defined as the result obtained by multiplying mean circumferential fiber shortening velocity by noninvasive end-systolic wall stress. FVP correlated with percent fibrosis in the myocardium, which was reflected by no other echocardiographic parameter. We also evaluated the prognostic values of the echocardiographic and histopathologic parameters. FVP had the highest value among them. We conclude that FVP is a very useful clinical parameter, with the further advantage of being obtained noninvasively.