According to echocardiographic observations, the hypertrophic left ventricle in hypertension and in aortic stenosis is inclined to asymmetric septal hypertrophy. The heart surgeon, after removal of the stenosed aortic valve, is not so rarely forced to resect an additional muscular hump of the basal ventricular septum. These findings contrast with our experiences from autopsy examinations; we see asymmetric septal hypertrophy only in hypertrophic cardiomyopathy (or coronary heart disease). The aim of this study was to demonstrate or refute this impression by measurements of the relevant parameters. In ten hearts with aortic stenosis and in 12 hearts of hypertensive patients there was no evidence of accentuated septal hypertrophy. In some hearts we found a prominent crista supraventricularis, which could explain the echocardiographic feature of a thickened ventricular septum. The muscular hump stenosing the left ventricular outflow tract can easily be explained by concentric hypertrophy. The thickness of the septum corresponded to that of the free wall, but only below the aortic valve did the hypertrophy become functionally relevant. There is no doubt that in certain cases this muscular hump has to be removed. The term asymmetric septal hypertrophy, however, is inadequate.