Background: Atrial septal defect (ASD) operation is a safe and low-risk procedure. Cosmetic results have been an important issue, so right ANTEROLATERAL thoracotomy (RALT) approach has been used for repair. However, in RALT, the skin incision usually crosses the future breast line, which may cause breast mal-development.Method: We reviewed the long-term results of a consecutive series of 406 patients from 1997- 2005 in whom the ASD was closed through a RALT or median sternotomy (MS) incision. 190 patients were male and 216 were female, with a mean age of 8.2±3.9 years. Defects repaired included 383ASD secundum (ASD 20) and 23 ASD sinus venosus type (ASD-SV). In 316 patients (77.8%), the defect was closed through MS, and 90 patients (22.2%) underwent RALT for repair.Result: The mean cardiopulmonary bypass time (CPB time) was 37.0±10 min. for MS vs. 40±11 min. for RALT (p=0.9, NS). Intubation time after operation was 9.0±5 hrs for MS and 8.1±7.1hr in RALT (p=0.8, NS). Postoperative drainage was 119mL (range, 0-1100mL) for MS and 94mL (range, 0-500mL) in RALT (p=0.1, NS). Postoperative pleural/pericardial effusion and pneumothorax occurred in 2.1% of patients in MS and 6.6% in RALT group (p= 0.001). There was no operative or late mortality, morbidity or breast mal-development in the long-term follow-up (range, 6 m -10 y, mean 4 yrs).Conclusion: RALT is a safe and effective alternative approach to MS incision for ASD closure.