Intraoperative thermal coronary angiography was successfully applied in 9 patients who underwent operative correction of congenital heart defects: arterial switch operation for transposition of the great arteries (n = 5), Ross operation for valvar aortic stenosis with regurgitation (n = 3), and aortic implantation of the left coronary artery for anomalous connection of the left coronary artery to the pulmonary artery (n = 1). Intraoperative thermal coronary angiography allows early detection and surgical correction of coronary ostial obstruction.