Objective: The type of congenital heart disease, early diagnosis, and treatment modality all play an important role in the morbidity and mortality of these diseases. This study examined the relationship between congenital heart disease and oxidative stress in children with cyanotic and acyanotic congenital heart disease. Materials and Methods: In this case-controlled cross-sectional study, the study groups consisted of 29 patients with cyanotic heart disease, 30 patients with acyanotic heart disease, and a control group of 32 healthy individuals. For all groups, the total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) were calculated. Of the cyanotic group, 12 were diagnosed with tetralogy of Fallot, 7 with transposition of the great arteries, 4 with tricuspid atresia, 4 with double outlet right ventricle and 2 with truncus arteriosus. In the acyanotic group 19 patients had ventricular septal defect (VSD), 5 atrial septal defect (ASD) and 6 patent ductus arteriosus (PDA). Statistical analyses were performed using Chi-square, Mann-Whitney U and Kruskal-Wallis tests. Results: The plasma TAS, TOS, and OSI were significantly higher in the cyanotic group than in the acyanotic group (p<0.0001, p<0.01, and p<0.01, respectively) and controls (p<0.0001, p<0.0001, and p<0.0001, respectively). A comparison between the acyanotic and control groups showed no statistical differences. Conclusion: The level of oxidative stress in patients with cyanotic congenital heart disease was significantly higher than in the acyanotic and control groups, which were similar.