Tetralogy of Fallot is the most common cyanotic congenital heart disease in children and is not difficult in diagnosis on the clinical and conventional radiographical ground. However, with these diagnostic methods, correct diagnosis of internal morphological anomalies cannot be made. Angiocardiography is the only method for the diagnosis of internal anomalies and their severity in Tetralogy of Fallot, and for the differenciation from Tetarlogy-simulating congenital cardiac anomaly. With recent advances in cardiac surgery, it is possible to perform total corrective surgery satisfactorily, and this in turn make angiocardiography an essential procedure in the diagnosis of Tetralogy of Fallot. Seventy cases of Tetralogy of Fallot diagnosed angiographically from 1971 to 1975 in Seoul National University Hospital were reviewed and compared with operative findings. The results are as follows: 1. Right ventriculography is the best method in the diagnosis of morphological anomalies of etralogy of Fallot, and findings are correlated well with operatice results. 2. Angiocardiography is the only method for the diagnosis of Tetralogy-simulating congenital heart disease, such as double outlet right ventricle with pulmonary stenosis and transposition complexes with pulmonary stenosis. 3. Angiocardiographic findings are valuable in the selection of good candidate for total correction of Tetralogy of Fallot.