El Assaad I, et al. - This study was sought to evaluate the effect of exercise stress echocardiography in children with hypertrophic cardiomyopathy. A retrospective review was designed to include all pediatric hypertrophic cardiomyopathy (HCM) individuals who had undergone exercise stress echocardiograph (ESE) at Boston Children's Hospital from January 2007 to June 2018. Individuals were classified into three groups (group 1: < 30 mm Hg at rest and exercise; group 2: <30 mm Hg at rest and ≥ 30 mm Hg with exercise; and group 3: ≥ 30 mm Hg at rest and exercise). This study enrolled a sum of 91 children (67% males) with median age 12 years (6-24 years) at first ESE and median left ventricle wall thickness of 20 mm formed the cohort. In this large series of pediatric patients with HCM, ESE can be performed safely and served as an effective tool to identify the lowest risk patients for cardiac outcome.