The electrocardiogram (ECG) in humans during childhood is somewhat paralleling the development of the human being: very complex and important changes over time. The adaptation from intra-utero live to live after birth generates significant changes and differences in comparison to the ECG of the adult. The screening for congenital or acquired myocardial diseases using the ECG provide rather easy ways of finding underlying threats for patients. In the setting of dysrhythmias the ECG is mandatory. The use of the ECG in diagnosis and treatment of congenital heart disease (CHD), has a lower importance - as morphology/function is of superior value - given by ultrasound, MRI/CT or catheter based data, but the ECG is useful in the follow-up of individuals with CHD. The variation of the normal ECG in children remains a challenge and urge a further request for larger data sets. Materials: Overview of ECG studies in different age groups in children and young adults with congenital heart disease. Results: Data provide a possible risk stratification in either CHD and congenital or acquired myocardial diseases. ECG - screening in children is implemented in many countries at rather low cost and significant benefit. Artificial intelligence-enhanced electrocardiogram analysis adds additional specificity and sensitivity in diagnosis of diseases and prediction of risks for arrhythmias. Discussion: The ECG in children is very important. Due to the rather large variation of normal ECG presentation in children, more data is needed in the care and prevention