PURPOSE: The major cause of cardiac dysfunction, after open heart surgery for congenital heart disease, is perioperative myocardial injury. Cardiac troponin I is found only within the myocardial cell, so it can be used as a biochemical marker of the myocardial injury. We performed this study to evaluate the worth of cardiac troponin I as a biochemical marker reflecting the extent of perioperative myocardial injury and recovery. METHODS: Thirty-four patients who had undergone elective open heart surgery of congenital heart disease(CHD) from April to July 2001 were enrolled in this study. We measured types of CHD, serial cardiac troponin I(baseline 1 day before operation, postoperative day 1, 2, 3, 7), duration of cardiopulmonary bypass(CPB), aortic cross clamping(ACC), intubation and postoperative hospital stay. RESULTS: Compared with the baseline before operation, there was a significant, increase of cardiac troponin I on the postoperative day 1 and a significant gradual decrease on the day 2, 3, 7. The levels of cardiac troponin I were the highest in the transposition of great artery(TGA) repair on the postoperative day 1 and high in the tetralogy of Fallot(TOF), atioventricular septal defect (AVSD), ventricular septal defect(VSD) and atrial septal defect(ASD) repair with decreasing sequence. The longer duration of CPB, ACC and intubation, the higher of cardiac troponin I, but there were no significant correlations between cardiac troponin I levels and duration of hospital stay. CONCLUSION: Because there was significant increases or decreases of cardiac troponin I according to the perioperative time and types of the congenital heart disease, it is a worthy biochemical marker which reflects the extent of perioperative myocardial injury and recovery after open heart surgery.