There are many different types of congenital heart defects. They range from simple defects with no symptoms to complex defects with severe, life-threatening symptoms. Defects such as coarctation of the aorta may not cause problems for many years. Other problems, such as a small ventricular septal defect (VSD), may never cause any problems, and some people with a VSD have normal physical activity and a normal life span. The study was carried out after the approval from the ethics committee. All the patients were explained about the possible adverse effects of contrast medium injection and radiation exposure. Informed signed consent was taken. The sensitivity and specificity in diagnosing overriding of the aorta using MDCT was 100% and 60% respectively. The P value was 0.0013 which was statistically highly significant. In our study the specificity was 60% as compare to the specificity of 100% this indicates that it is relatively good value. This indicates that the number of cases interpreted as positive for overriding of the aorta were more in comparison to the peroperative findings