Idiopathic ventricular tachycardia (IVT) is a rare arrhythmia in children. A great deal of uncertainty and numerous questions still remain regarding the extent of investigation, therapy, and long-term prognosis for children with IVT. The existence of subclinical cardiac disease, as well as of autonomic dysfunction in patients with ventricular arrhythmias, has been well documented. A number of experimental and clinical studies have suggested that imbalances within the cardiac autonomic system\'s activity may be crucial in the generation of ventricular tachycardia, irrespective of the presence of cardiovascular pathological substrate. Heart rate variability (HRV) analysis provides a useful method for measuring the autonomic activity. This study evaluates HRV in children with IVT. The study included 31 children with ventricular arrhythmia who were divided into two groups: (1) patients with frequent ventricular extrasystoles (VES) and (2) patients with IVT. The control group comprised 23 healthy children without pathological findings on 24-h ECG Holter. Twenty-four-hour ambulatory electrocardiography recordings were obtained, and the time-domain variables were calculated. HRV was compared to age-related normal values. It was observed that the overall heart rate variability is diminished in children with IVT. We recommend HRV analysis of any child with IVT. Quantification of the autonomic nervous system activity using time domain analyses may be a helpful diagnostic tool in the clinical assessment and initial evaluation of these children.