[Objective] The presence of intact or highly restrictive atrial septum(HLHS/IAS or HLHS/HRAS) has been recognized as one of the risk factor for the treatment of hypoplastic left heart syndrome (HLHS). We have introduced a new hybrid strategy to the patients with HLHS associated with IAS/HRAS. This new technique included bilateral pulmonary artery banding(PAB) and balloon atrial septostomy(BAS) without using cardiopulmonary bypass(CPB).[Patients and Methods] Bilateral PAB was performed as a first palliation to 9 high risk neonates with HLHS from October 2005 to October 2008. Four patients out of 9 had a IAS/HRAS and bilateral PAB and BAS was applied under echo-guidance without CPB. There were 3 IAS and 1 HRAS. All 4 patients underwent re-BAS with 1 failure and 1 patient required stent to restenosed atrial septum.Two of them had a prenatal diagnosis and underwent this new technique within 1 and 2 hours after birth. Both of them survived and underwent rapid stage Norwood with RV-PA and BDG successfully. Other 2 patients had no pre-natal diagnosis and emergency surgery was applied at day1 and day3 with a same technique. Both of them died after rapid stage Norwood with RV-PA due to pulmonary hypertension. [Conclusion] Mortality to neonates with HLHS/IAS or HLHS/HRAS remains high, however new hybrid strategy including bilateral PAB and BAS without CPB may improve long term survival if it is done before irreversible pulmonary vascular damage.