PURPOSE: This study aimed to investigate cardiac electrical and autonomic function, the longitudinal changes, and the associated risk factors in children with Dravet syndrome (DS). METHODS: Twenty-four children with DS (11 boys, 13 girls; mean age, 7.2 +/- 2.9 years) and 21 control subjects (9 boys, 12 girls; mean age, 8.2 +/- 3.0 years) were enrolled in this study. P dispersion, QTc and QTc dispersion, and heart rate variability (HRV) were evaluated using standard electrocardiography and 24-hr Holter monitoring at the initial and follow-up study of the 6-12 months intervals. RESULTS: The DS group had significantly higher P dispersion (p = 0.017), QT and QTc dispersion values (p < 0.001 for two parameters) than the control group. Most HRV parameters, such as SDNN (p < 0.001), SDANN5 (p < 0.001), SDANN-index (p = 0.001), and RMSSD (p = 0.006) were all significantly lower in the DS group than in the control group. The mean values of initial QTc, QTc dispersion, and HRV parameters showed significantly increase (QTc and QTc dispersion) and decrease (HRV) in the follow-up study (mean duration: 1.2 +/- 0.5 years) in 13 DS children. +/- On multivariate regression analysis, epilepsy duration had an independently significant effect for the longitudinal change of QTc, QTc dispersion, and HRV. CONCLUSIONS: DS children had significant different values of cardiac electrical and autonomic function compared with control group. Particularly, longer duration of epilepsy was significantly negative effect on the longitudinal change of cardiac autonomic function.