OBJECTIVE: The prevalence of bowel and bladder dysfunction, hyperhidrosis, and poor cardiopulmonary endurance is higher for children with cerebral palsy than for the general population. The purpose of this study was to investigate the autonomic function for patients with cerebral palsy. DESIGN: Thirty patients with cerebral palsy and 30 control subjects were enrolled in this study. Power spectrum analysis of heart rate variability was performed under standardized conditions. RESULTS: In both the supine and head-up positions for test subjects, there was no significant difference for the low frequency component of heart rate variability, high frequency component of heart rate variability, or the low frequency/high frequency ratio between the study and control groups. A significantly greater low frequency component of heart rate variability, smaller high frequency component of heart rate variability, and greater low frequency/high frequency ratio while in the head-up position compared with the supine position was noted for the control group, which implies normal sympathovagal balance. A similar phenomenon was not observed for the study group. CONCLUSIONS: The disturbed balance of activity between the sympathetic and parasympathetic nervous system observed in the study might result from the loss of hemispheric influence in patients with cerebral palsy; however, further investigation is clearly necessary.