OBJECTIVE: To study erythrocyte oxidative stress status and its association with left to right shunt congenital heart disease (CHD) in children. METHODS: A total of 31 children with left to right shunt CHD were enrolled, including 7 cases of atrial septal defect (ASD), 12 ventricular septal defect (VSD), 4 patent ductus arteriosus (PDA), 6 patent foramen ovale (PFO), and 2 complete endocardial cushion defect. Twenty healthy age-matched (1 month to 3 years old) children severed as the control group. The contents of superoxide dismutase (SOD) and malonaldehyde (MDA) in erythrocytes were determined using ELISA. ESR was measured by Westergen. PaO2 and PaCO2 were measured by Blood Gas Analyzer (GEM Premier 3000). RESULTS: The MDA content in erythrocytes in the CHD group was significantly higher, in contrast, SOD content was significantly lower than that in the control group (P<0.05). The CHD children with heart failure had more decreased SOD and more increased MDA contents compared with the control group (P<0.01). The SOD level was the highest in the PFO group and was the lowest in the complete endocardial cushion defect group. The SOD level in the PFO group was significantly higher than that in the ASD, VSD and complete endocardial cushion defect groups (P<0.05). The MDA level was the highest in the VSD group and was the lowest in the complete endocardial cushion defect group. There were significant differences in the MDA level among CHD subgroups (P<0.05). The ESR was negatively correlated to the SOD level (r=-0.191, P<0.05), while positively correlated to PaO2 level in CHD children (r=0.216, P<0.05). There was a negative correlation between SOD and MDA levels (r=-0.312, P<0.05). CONCLUSIONS: Oxidative stress exists in children with left to right shunt CHD. The SOD and MDA contents in erythrocytes can be used as markers for the assessment of severity of the disease. ［Chin J Contemp Pediatr, 2010, 12 (6):440-443］