Cardiovascular complications are the leading causes of morbidity and mortality in adult dialysis patients. The aim of this study was to evaluate the cardiovascular system of children on hemodialysis (HD), with special focus on rhythm disturbances. Nine patients, aged 15.6+/-4.1 years, underwent electrocardiographic examination (ECG) including 12-lead ECG, Holter-ECG, QT dispersion, signal-averaged ECG, and exercise testing. Echocardiography and 24-h blood pressure measurement were also performed. Patients had been on HD for a median period of 7 months (range 1-29 months). Normal findings were obtained with 12-lead ECG, exercise testing, QT dispersion, and signal-averaged ECG. Holter-ECG showed short runs of slow monomorphic ventricular tachycardia in two patients. Echocardiography was normal except for ventricular hypertrophy in two patients. In conclusion, rhythm disturbances were rare, with slow monomorphic ventricular tachycardias being the only significant finding. The absence of late potentials and normal QT dispersion suggest that myocardial electrical excitability and recovery are preserved in children on HD.