To investigate the relationship between regional contractile dynamics and regional myocardial lesions of the left ventricular wall in patients with hypertrophic cardiomyopathy (HCM), autopsy findings of 11 patients were compared with their ante mortem echocardiographic findings. The regional systolic wall thickenings (%RWT) of the interventricular septum (IVS) and left ventricular posterior wall (LVPW) obtained using M-mode echocardiography were converted into % normalized RWT (%NRWT) by the averaged %RWT in 15 normal subjects. The %NRWT was compared with the wall thickness obtained by echocardiography and/or autopsy, and histological findings, such as the myocardial fibrosis ratio, disarray area ratio, and mean myocyte diameter. 1. There were no significant correlations among wall thickness of the left ventricle, the myocardial fibrosis ratio, the disarray area ratio, and the mean myocyte diameter of each segment. 2. The %NRWT in 22 segments of the 11 patients with HCM was not significantly related to the echocardiographic wall thickness at end-systole, the autopsy wall thickness, the mean myocyte diameter and the disarray area ratio, but that correlated significantly with the echocardiographically-determined wall thickness at end-diastole (r = -0.53, p less than 0.02), and with the myocardial fibrosis ratios (r = -0.59, p less than 0.005). 3. The %NRWT in the IVS was significantly less than that in the LVPW. The %NRWT in all segments of the LVPW was significantly related to the myocardial fibrosis ratios (r = -0.80, p less than 0.005), but was not related to the wall thicknesses or the disarray area ratios.(ABSTRACT TRUNCATED AT 250 WORDS)