Purpose We aimed to evaluate the autonomic nervous system activity in children with overactive bladder (OAB) syndrome.Methods Included in the study were 40 children with overactive bladder and 28 healthy controls. Autonomic tests were performed on all participants, including heart rate interval variation (RRIV), heart rate response to valsalva maneuver, and sympathetic skin response (SSR).Results Mean valsalva rates in the overactive bladder and control groups were 1.530.29 and 1.30 +/- 0.18, respectively, a statistically significant difference (P<0.001). Also significantly different were deep breathing RRIV values of the study and control groups: 56.65 +/- 14.66 and 47.92 +/- 10.15, respectively (P=0.008). No statistical differences were found in SSR when OAB patients were compared with controls (P>0.05).Conclusions This study demonstrated a parasympathetic hyperactivity in children with OAB, results suggesting a dysfunction in their autonomic nervous systems. (C) 2016 Wiley Periodicals, Inc.