Background: Heartbeat abnormalities, such as when it beats too quickly or too slowly, are known as cardiac arrhythmias. Although certain arrhythmias are more common in neonates and young infants compared to older children and adults, all types of arrhythmias can occur. Many are benign and do not cause hemodynamic compromise. Others may compromise cardiac output and cause decreased blood pressure and decreased perfusion. Arrythmias can be due to abnormal structure of the heart, cardiomyopathy, inherited diseases, drugs, infections, inflammation, systemic diseases, autoimmune diseases, mechanical ventilation, central venous line insertion, electrolyte disturbance and others. Not all arrhythmias provide the same risk to the patient, despite the fact that they are frequently seen in critically ill patients. Certain arrhythmias, for instance, can be benign and self-limiting, whereas others might swiftly worsen and become potentially fatal. Aim: An overview of the most frequent causes of arrhythmias in children with acquired or structurally congenital cardiac disorders is provided in this article. Conclusion: In pediatric patients there are wide range of causes for arrhythmias. May be caused by primarily diseases, or acquired factors.