Background: Adults with growth hormone deficiency (GHD) have a number of cardiovascular risk factors that may enhance their risk of cardiovascular morbidity and mortality. The impact of growth hormone (GH) therapy on heart function and metabolic abnormalities that may increase children's risk of cardiovascular disease (CVD) at an early age has been the subject of very few research in children. Aim: To evaluate the effect of growth hormone therapy on left ventricular mass. Patients and methods: This prospective cohort study was carried out at Pediatric Cardiology and Endocrinology Units of Children's Hospital and Clinical Pathology Laboratory, Faculty of Medicine, Zagazig University. In total, 41 people took part while studying. Two groups were created out of them: those with idiopathic short stature, which included 16 children, and those with growth hormone insufficiency, which included 25 children. To determine LV mass, Echocardiography was used. Results: The left ventricular mass increased in a statistically meaningful way (from 83.4 g to 89.57 g) after GH therapy. Conclusion: LV mass increased remarkably in our patients after GH therapy .LV mass correlated positively with duration of GH therapy and negatively with the percentage of final height to lowest target height.