To evaluate the invasiveness of a minimal access approach for simple congenital heart defects, and determine whether it can be regarded as a standard operation, 83 patients with an atrial septal defect and 73 with a ventricular septal defect underwent repair through a minimal skin incision and lower partial median sternotomy. There were no operative deaths, severe intraoperative complications, or conversion to full sternotomy. The clinical course of 106 patients was compared with that of 21 treated using a full sternotomy by the same surgeon; there were no significant differences, except in the operative time for ASD patients. The clinical courses of 2 minimal access subgroups (50 patients operated on by residents and 106 treated by the staff surgeon were compared; operative time, bypass time, ventricular fibrillation time (ASD repair), and cardiac arrest time (VSD repair) were significantly shorter in those operated on by the staff surgeon, but there was no difference in clinical course. The minimal access approach produced good cosmetic results, its invasiveness was similar to that of a full sternotomy, and it may be considered a standard operation for pediatric patients with septal defects.