AIM:To explore the safety of anesthesia for neonates by studying the effects of general anesthesia (GA) and spinal-epidural anesthesia (SA) on the levels of lactic acid, S100B, superoxide dismutase (SOD) and malond-ialdehyde ( MDA) in the umbilical cord blood and placental stereological changes .METHODS:The singleton , term preg-nancy of 50 patients for elective cesarean section were assigned to 2 groups:GA group and SA group , with 25 patients in each group.Blood pressure (BP) and heart rate (HR) of the parturient women were monitored and recorded at 6 time points.The Apgar score was calculated at 1 min and 5 min after birth.The gas analysis of the umbilical artery blood , S100B protein concentration, blood lactic acid, SOD and MDA were also measured .Stereological evaluation of the vascular adaptations in the human placental villous capillary was performed .RESULTS:BP, HR, Apgar scores, gas analysis, the pH value of the umbilical artery blood , the serum concentrations of S 100B protein and the length density of villous capillar-ies had no significant change between the 2 groups (P>0.05).The levels of blood lactic acid and SOD in GA group were significantly lower than those in SA group (P<0.01).MDA content and volume density of villous capillaries in GA group were significantly higher than those in SA group ( P<0.01 ) .CONCLUSION: General anesthesia for cesarean section was safety for neonates .However, as indicated by the oxidation index , general anesthesia may have some harmful effect on the neonates by oxygen free radicals .