BACKGROUND: It is well documented that BIS reflects the level of sedation but conflicting results exist about whether BIS can reflect the depth of anesthesia. We intended to identify this issue by investigating the correlation between the pre-incision bispectral index (BIS) values and the hemodynamic responses to skin incision during sevoflurane-N2O anesthesia in children. METHODS: In total, 117 ASA physical status I or II pediatric patients, aged 6 mo-12 yr, were enrolled. After induction and intubation with thiopental, rocuronium, sevoflurane and N2O, patients were randomly allocated to one of the four end-tidal sevoflurane concentrations (ETsevo); 2.0, 2.5, 3.0, and 3.5 %; with 60% N2O. The ETsevo was maintained constant for more than 15 min before and 5 min after skin incision. BIS, heart rate (HR), and systolic arterial pressure (SAP) before and after skin incision were recorded. RESULTS: Although there were no correlation between pre-incision BIS and change in BIS, SAP, and HR (Pearson's coefficient -0.120, -0.102, and -0.080, respectively), there were correlations between changes of BIS and changes in SAP and HR (Pearson's coefficient 0.318 and 0.309, respectively, P < 0.05). CONCLUSIONS: There was a correlation between the change of BIS, but not BISpre, and change in hemodynamic variables with skin incision during sevoflurane anesthesia in children.