Objectives: Children with Turner syndrome (TS) are at increased risk of cardiovascular disease (CVD), but associations with subclinical CVD are not well-characterized. The purpose of this study was to assess myocardial function using strain imaging (SI) by echocardiography in children with TS and without known CVD. Methods: The study included 48 children with TS aged 4-16 years and 20 healthy control children. Children with TS were excluded if they had a cardiac malformation, a decreased left ventricular (LV) systolic function, or any chronic disease. Each child had an echocardiographic examination with conventional echocardiography and one-dimensional longitudinal strain (1DST) echocardiography. Results: Septal and lateral systolic strain (S) and strain rate (SR) values, which are indicative of longitudinal myocardial function, were significantly decreased in TS patients. However, LV ejection fraction (LVEF) and LV fractional shortening (LVFS) was not significantly different between groups. LV mass index (LVMi), interventricular septum (IVS) thickness, LV posterior wall (LVPW) thickness, and left atrial (LA) diameter index were significantly higher in TS children compared to controls. Peak transmitral flow velocity in late diastole (peak A) was significantly higher, whereas peak transmitral flow velocity in early diastole (peak E), deceleration time (DT), and the ratio of early to late diastolic filling were significantly lower, in TS patients. Conclusion: Reduced LV systolic S and SR in children with TS may indicate early myocardial dysfunction before any detectable change in LVEF.