Aim. To assess echocardiography data of the main structural myocardial changes in children with WPW-syndrome. Material and methods. The study included 26 children with WPW-syndrome without organic cardiac pathology and 24 healthy children (comparative group). All children underwent electrocardiography, Holter-ECG, echocardiographic examination according to R. Devereux (1982) and B. Marón (2005) criteria with calculation of Z-factors for the main cardiac anatomical structures and myocardial mass index by Pettersen M.D technique (2008) in A.S. Sharykin modification (2013) to detect myocardial remodeling. The research was conducted at specialized cardiologic department within 3 years. Results. Morphological and functional myocardial changes were revealed in both groups. There were significant changes of left ventricular end-systolic dimension, systolic LV posterior wall thickness (PWT), diastolic interventricular septum thickness, systolic interventricular septum thickness, left atrial dimension, LV ejection fraction. So, arrhythmogenic myocardial dysfunction in children with WPW-syndrome including hemodynamic changes and impaired contractility is present. Conclusion. Significant changes of morpho-functional parameters of the heart confirm arrhythmogenic myocardial dysfunction in children with WPW-syndrome.