Introduction: Migraine is a common neurovascular disease characterised with recurrent attacks by pain-free periods. It has been suggested that both sympathetic and parasympathetic dysfunctions play a role in its pathophysiology. Aim: The aim of our study was to investigate the ECG changes during attack-free period in children with migraine, in terms of QTc interval, QTc, and P-wave dispersion to evaluate the autonomic nervous system disturbance. Methods: Sixty children who were diagnosed with migraine were included as patient group and 50 healthy, age- and body mass index-matched children who were examined for innocent murmur were included as control group. The patients' routine ECG records were screened from the outpatient clinic files. The durations of P-wave, QT, and QTc intervals and dispersion values and heart rates (beats/minute) were compared between the patient and control groups. Results: P maximum and P dispersion were significantly higher, and P minimum was significantly lower in the migraine group compared with the control group. QT-QTc maximum and QT-QTc dispersion were significantly higher and QT-QTc minimum was significantly lower in the migraine group compared with the control group. Conclusion: According to our findings, although migraine patients were asymptomatic and no arrhythmia was detected in the surface ECG, sympathovagal balance in the sympathetic system, which may be disrupted in favour of the sympathetic system, should continue even in the attack-free period, and we should be careful in terms of serious arrhythmias that may develop in these patients.