AIM: To assess parameters of heart rate turbulence in patients with ventricular extrasystoles (VES). MATERIAL AND METHODS: Patients with VES during Holter ECG monitoring (n=65, age 1-17 years, 32 girls, 33 boys) including 3 with long QT syndrome, 4 with catecholaminergic ventricular tachycardia, 1 with arrhythmogenic right ventricular dysplasia, 4 with dilated cardiomyopathy, 2 with Brugada syndrome, 3 with Duchenne myopathy, and 48 with idiopathic VES. Parameters HRT onset and slope were calculated for 1678 VES. During follow-up (6+/-4.9 years) deaths, sudden deaths, and such complications as syncope, cardiac dilatation, heart failure were registered in 26 patients. RESULTS: HRT slope exceeded 2.5 ms/RR in all patients. HRT onset was >0 in patients with catecholaminergic ventricular tachycardia, dilated cardiomyopathy, and Duchenne myopathy. The following complications occurred in 7 of 8 patients (87.5%) with HRT onset >0: syncope, sudden deaths (2 patients with dilated cardiomyopathy), dilatation of cardiac chambers, tolerance to antiarrhythmic therapy. Patients with long QT syndrome and arrhythmogenic right ventricular dysplasia (including 2 who afterwards died suddenly) had normal HRT onset. The sensitivity and specificity of HRT onset measurement for unfavorable prognosis of VES was 27 and 97%, respectively. No relationship was found between HRT slope and onset (r=-0.057). CONCLUSION: Pathological HRT (mainly represented by changes of HRT onset) are characteristic for organic myocardial diseases. Therefore detection of abnormal HRT dictates necessity of exclusion of organic cardiac pathology.