OBJECTIVE: To study the diagnostic value of heart rate variability (HRV) in heart dysfunction in children with beta-thalassemia major (beta-TM)by examining the changes of HRV in beta-TM children. METHODS: A 24 hours Holter monitoring electrocardiogram (Holter) was performed in 21 children with beta-TM and 15 healthy children (control group). The time domain and frequency domain indexes of HRV in the two groups were compared. The correlation between serum ferritin levels and HRV was evaluated. RESULTS: The time domain indexes SDNN, rMSSD and PNN50 and the frequency domain indexes very low frequency (VLF), low frequency (LF) and high frequency (HF) in the beta-TM group were significantly lower than in the control group (P<0.05). There was no correlation between serum ferritin level and HRV in children with beta-TM. CONCLUSIONS: The autonomic nerve dysfunction exists in children with beta-TM. HRV analysis is useful in the prediction of early cardiac dysfunction in children with beta-TM.