Two patients with hypertrophic cardiomyopathy and a previously unreported distribution of left ventricular hypertrophy are described. Each patient showed substantial wall thickening that was confined to the posterobasal segment of the left ventricular free wall, as well as evidence of dynamic subaortic obstruction. This observation emphasizes the fact that hypertrophic cardiomyopathy is characterized by a broad morphologic spectrum. Furthermore, it demonstrates a unique circumstance in which left ventricular outflow tract obstruction may occur in the absence of anterior and basal septal hypertrophy.