Background: Some patients with congenitally corrected transposition of the great arteries (CTGA) have been diagnosed incidentally in adult stage. It is hypothesized that atrioventricular discordance in CGTA would cause electrical abnormalities. Methods: We included 40 patients who were diagnosed as CTGA over 18 years old. Initial electrocardiograms without artificial pacing were analyzed. Results: Mean age were 39짹14 years old (18 to 76) and female were 21 (53%). Associated anomalies were 4 ventricular septal defect, 6 atrial septal defect, 3 pulmonary stenosis. No patient has the evidence of myocardial infarction. Electrocardiographic characteristics were summarized in Table. Conclusions: In adult patients with CTGA, electrocardiographic characteristics were AV conduction disturbance, left axis deviation, clockwise rotation and pathologic Q wave in inferior leads.