Supraventricular tachycardias (SVTs) are observed in 0,1-0,4% of the paediatric population and represent an important clinical problem with related significant health and social issues. Most tachycardias are paroxysmal, being associated with sudden onset and termination, and only a relatively small number of them is permanent, namely chronic. Paroxysmal tachycardias, in addition, can be either sustained (lasting > 30 seconds) or non-sustained whenever their duration is less. Most SVTs are due to re-entry, and only atrial tachycardia and and junctional ectopic tachycardia are caused by enhanced automaticity. Atrial tachycardia, however, can also be due, although rarely, to re-entry or to triggered activity. A prompt recognition of these arrthmias in children by pediatric cardiologist is essential for a correct clinical managemet of the patients. In this review, the epidemiologic data regarding the SVTs in pediatric age are reported along with the description of the pathophysiological mechanisms and the analysis of electrocardiographic findings to be considered for a correct clinical diagnosis and a rational therapeutic approach to these arrhythmias.