Background: The mercury sphygmomanometer has been the gold standard used for obtaining blood pressure (BP). However, due to environmental concerns and more use of automated BP devices, an alternative to using the standard mercury sphygmomanometer to measure BP. Aim: The aim of this study is to determine the reliability of Automatic Blood Pressure Monitor (ABPM) for measuring the blood pressure in children. Methods: One thousand children were enrolled in this study. Those who were critically ill and those who did not give consent were excluded .The accuracy of Omron HEM–7121 BP readings was compared with that of mercury BP device readings. All children rested for 5 min prior to the first BP reading. Each children had four BP measurements recorded sequentially i.e. two valid systolic readings, and two valid diastolic readings by both methods. Results: BP taken with the automated (OMRAN) device was systolic 104.71±6.75 and diastolic was 67.90±6.89. Compared to systolic 107.82±7.49, and mean diastolic of 69.61±7.21 measured by manual mercury sphygmomanometer BP readings (P < 0.001). The comparison of the manual versus the automated readings showed a high coefficient of correlation (r2) for systolic BP (r2 =0.86) and diastolic BP (r2 = 0.89) readings. Comparison of mean differences between automated and manual measures showed the automated machine consistently under-read both systolic and diastolic blood pressures. Linear regression analysis showed that the automated systolic BP and is a significant predictor (b = 0.864P < 0.001) of manual systolic BP. Similarly, automated diastolic BP was also a significant predictor (b = 0.806, P < 0.001) of manual diastolic BP. Conclusions: This study concludes that the automated blood pressure device is reliable and accurate for measuring the BP in children. So, conventional manual BP readings can be replaced by readings taken using a validated, automated BP recorder in population surveys.