Abstract: Background: Cardiovascular disease is the leading cause of mortality among patients on chronic hemodialysis (HD). 30% of the deaths in these patients are due to cardiac arrest, death of unknown cause or cardiac arrhythmia. The increasing time of ventricular depolarization and repolarization, measured by QT interval duration on the electrocardiogram (ECG) at rest, has emerged as a predictor of complex ventricular arrhythmias. Objectives: To determine ECG alterations in chronic (HD) children before and after HD. Design: Cross sectional study. Setting: Pediatric HD unit of Sohag University Hospital, Sohag, 2016. Methods: after obtaining consents from all patients less than 18 years on dialysis, they were submitted to the examination of a 12-lead ECG: heart rate, QRS duration, QRS amplitude, T-wave amplitude and QT interval was measured 10 min pre and post-HD, and QT interval was corrected for heart rate using Bazett’s formula. Children were monitored during dialysis session by 3 leads ECG to detect any sustained arrhythmia. Main outcome measures: 12-lead electrocardiogram. Results: 20 patients on regular HD were included in the study. 75% of them were females; the average age was 12.9 (3.7) years old and 55% of all patients had QTc prolongation before dialysis. No significant QTc prolongation occurred after dialysis. HD leaded to a significant increase in the QRS explained by the decrease of the extracellular fluid and blood volume and hence a decrease of the cardiac preload. HD also decrease of the T-wave amplitude explained by potassium decrease during HD. PVCs observed in the ECG of 3 children after dialysis. No sustained arrhythmias occurred to our patients during dialysis sessions. Conclusion: children on chronic HD had high frequency of abnormal ECG findings, especially prolonged QTc interval. Limitation: the studied cohort was small that may weaken the statistical power of the study.