Arrhythmias include abnormalities in heart rate or rhythm; the incidence of this condition in the general pediatric population is estimated at 55.1 per 100,000 consultations in children’s emergency units and tends to have a bimodal distribution. The most common arrhythmias in this group include sinus tachycardia, supraventricular tachycardia, bradycardia, premature ventricular and supraventricular contractions. This work aims to review the clinical, electrocardiographic characteristics and general management of the main arrhythmias described. Sinus tachycardia corresponds to a discharge of the sinus node with a frequency greater than normal for the patient’s age; it usually corresponds to a compensatory response to the increased metabolic demand of the body. Supraventricular tachycardia is a generic term used to refer to arrhythmias originating above the ventricular tissue. There are different mechanisms responsible, the main one being atrioventricular reentry; most of these patients have a structurally normal heart. Acute management varies according to hemodynamic stability; in stable cases the pillars correspond to vagal maneuvers and adenosine. Another important condition is long QT syndrome, which corresponds to a disorder of ventricular repolarization. It can be of congenital or acquired origin, responsible for 3,000 to 4,000 cases of sudden death per year in the United States. It has a risk of progression to a particular arrhythmia called Torsade de Pointes (TdP), which consists of a potentially fatal polymorphic ventricular tachycardia, which has specific management with magnesium sulfate. In relation to bradyarrhythmias, sinus bradycardia is the most common, it can be associated with vagal stimulation, acute elevation of intracranial pressure, acidosis, hypoxemia, the latter being the most frequent cause.