PURPOSE: The aims of this study are to investigate the results of balloon aortic valvuloplasty (BAV) in congenital aortic stenosis(CAS) and, especially, to compare the results between BAV performed before two months of age(Group A) and BAV after two month of age(Group B). METHODS: From January 1993 to June 2000, 14 patients who were diagnosed as CAS were treated with BAV. Indications for BAV were 1) critical aortic stenosis and 2) a peak-to-peak systolic pressure gradient in excess of 50mmHg or a gradient > OR =40mmHg with either symptoms or EKG changes. RESULTS: In Group A, the procedures were performed through femoral artery, carotid, or femoral vein approach. In Group B, however, all procedures were performed through femoral artery approach. After the BAV, a peak-to-peak systolic pressure gradient was reduced from 66.5+/-31.3 mmHg to 30.1+/-15.5mmHg(Group A; from 42.3+/-23.8mmHg to 22.0+/-15.3mmHg, Group B; from 88.9+/-16.8mmHg to 38.1+/-11.5mmHg). Repeated BAV were tried in 3 of these cases. There were 3 mortality cases in Group A. One of them was related with the procedure. CONCLUSION: The result of BAV after 2 months of age is acceptable, but that before 2 months of age is not satisfactory. However this result of BAV on early infants is thought to be mainly related to the poor pre-BAV conditions. So BAV may still be considered as a first intervention for CAS in this period. In such cases, other approachs rather than femoral artery should be considered.