This study included 54 normotensive children with documented history of parental essential hypertension (group 1) .They were 31 males and 23 females and their age ranged frome 8-16 years.Also 20 normotensive children without history of parental essential hypertension were included as control (group 2) .They were 12 males and 8 females of matched age and sex with group 1 .Our results revealed that there was statistical significant difference between group 1 and group 2 as regard resting heart rate (HR) ,diastolic blood pressure ( DBP) .Also there was statistical significant difference between group 1 and group 2 as regard HR,DBP and systolic blood pressure (SBP) throughout exercise stress test . In this study the left ventricular mass (LVM) showed statistical significant difference between with family history of essential hypertension and control group .There was statistical significant difference in (E/A ratio ) diastolic function between group 1 and group 2 .LVM was significantly correlated with age ,DBP,and E/A ratio .There was no statistical significant difference between group 1 and group 2 as regard ejection fraction (EF) .These findings indicate that an altered hemodynamic regulatory mechanism may exist before the clinical detection of hypertension . Zagazig University Medical Journal ,Vol.4,no.1,Jan.1999