AbstractBackgroundRadiofrequency ablation (RFA) is the standard method of treatment for tachyarrhythmias in school children, and it leads to complete recovery in children without structural heart disease. However, RFA in young children is limited by the risk of complications and unstudied remote effects of radiofrequency lesions.ObjectiveTo present the experience of RFA of arrhythmias and the results of follow‐up of younger children.Materials and MethodsRFA procedures (n= 255) were performed in 209 children with arrhythmias from 0 to 7 years old. The arrhythmias were presented with atrioventricular reentry tachycardia with Wolff‐Parkinson‐White (WPW) syndrome (56%), atrial ectopic tachycardia (21.5%), atrioventricular nodal reentry tachycardia (4.8%), and ventricular arrhythmia (17.2%).ResultsThe overall effectiveness of RFA, considering the repeated procedures performed due to the primary ineffectiveness and recurrencies, was 94.7%. There was no mortality associated with RFA in patients, including young patients. All cases of “major” complications are associated with RFA of the left‐sided accessory pathway and tachycardia foci and are represented by the mitral valve damage in three patients (1.4%). Tachycardia and preexcitation recurred in 44 (21%) patients. There was a correlation between recurrences and parameters of RFA (odds ratio 0.894; 95% confidence interval: 0.804–0.994;p= .039). Reducing the maximum power of effective applications in our study increased the risk of recurrence.ConclusionThe use of the minimum effective parameters of RFA in children reduces the risk of complications, but increases arrhythmia recurrence rate.