Background: We aimed to evaluate the incidence, type, and management of supraventricular tachyarrhythmias (SVT) during the first year of life in a retrospective, population-based, single-center study during a 10-year period., Methods: The analyzed patient cohort is based on data from the only specialized center managing all cases of neonatal and infant SVTs between 2009 and 2018 in the Slovak Republic (5.5 million population). A total of 116 consecutive patients <366 days old were included in the study., Results: Calculated SVT incidence ratio was 1:4500 in the first year of life. AV reentry tachycardia was the leading arrhythmia (49%). SVT in this specific population was frequently a transient problem with spontaneous resolution in 87% of patients during a median 3-year follow up. Congenital heart disease was common (16%). Intrauterine treatment by drugs administered to mother was safe and effective in preventing unnecessary cesarean deliveries. In arrhythmia termination, amiodarone and propafenone were equally safe and effective, with possible more favorable pharmacodynamics of the former. For prophylactic treatment, sotalol and propafenone were equally safe and effective and became the preferred basis of long-term drug therapy in our center. However, this therapy requires intensive monitoring during its initiation., Conclusion: The prognosis of SVT in the first year of life is good: with optimized pharmacological treatment, the need for early catheter ablation and mortality rate are low (<1%) and there is a high rate of spontaneous arrhythmia resolution. Heart failure is a possible predictor of arrhythmia persistence with need for ablation in later life., (© 2020 Wiley Periodicals LLC.)