We report a case of a 10-year-old child with nonobstructive hypertrophic cardiomyopathy in whom two-dimensional echocardiography showed asymmetric septal hypertrophy with a localized thickening in the mid-septal segment. Systolic regional longitudinal motion and deformation indices were quantified by the new ultrasound-based parameters velocity, strain rate, and strain. Regional longitudinal myocardial function indices were normal for the basal and apical septal segments. The deformation parameters strain rate and strain (not the regional velocity profile) were abnormal only in the hypertrophied mid-septal segment with myofibril disarray. The concepts and advantages and clinical implications behind this quantitative approach to localizing and quantifying areas of abnormal deformation related to such myocardial disarray in localized hypertrophy are discussed.