The aim of this study was to examine early left ventricular systolic and diastolic changes using tissue Doppler imaging (TDI) in normotensive children of hypertensive parents (NCHP), a risk group for cardiovascular diseases. Ninety-two children characterized as NCHP (age range: 6-18 years) and 90 age-, gender-, height-, weight-, and body mass index-matched children characterized as normotensive children of normotensive parents (NCNP) were included in the study. Left ventricular diastolic parameters were assessed using transmitral flow pulse wave Doppler echocardiography and mitral septal and lateral annular TDI. Left ventricular systolic and diastolic function was evaluated globally using the TDI-derived myocardial performance index (MPI'). Mean systolic, diastolic, and average blood pressure values were found to be higher in the NCHP group than in the NCNP group. Echocardiographic parameters in the NCHP group showed statistically significant differences, including increased interventricular septum end-diastolic wall thickness (p = 0.039), left ventricular end-diastolic posterior wall thickness (p = 0 .011) , relative wall thickness (p = 0 .013) , and transmitral flow A velocity (p = 0.003); parameters determined by TDI included a prolonged isovolumetric relaxation time (p < 0.001) and isovolumetric contraction time (p = 0 .002) , shortened ejection time (p = 0.001), and increased MPI' (p < 0.001) in the NCHP group. Early alterations in myocardial function, indicated by increased MPI' values, had a positive correlation with systolic blood pressure and myocardial thickness. Conversely, they were negatively correlated with the ejection fraction and E/A ratio, which decreases with diastolic dysfunction. The MPI' is considered a repeatable, non-invasive, and low-cost assessment method that can surpass conventional methods in the detection of early left ventricular systolic and diastolic functional changes in the subclinical period of hypertension in children with familial risk.