The purpose of this study was to establish a useful cut-off level for performing an original Rastelli-type operation in patients with transposition of the great arteries (TGA)/ventricular septal defect (VSD) or double outlet right ventricle (DORV). A total of 43 patients with TGA/VSD or DORV who underwent an original Rastelli-type operation in this institute between March 1993 and January 2009 were reviewed retrospectively. These patients were divided into two groups using the length between the top of the interventricular septum and the aortic valve (IVS-AV length); Group A; IVS-AV length <80% of normal left ventricular end-diastolic diameter (LVDd). Group B; IVS-AV length > or =80% of normal LVDd. Group A had a significantly better survival than Group B (100% vs. 56%, P=0.001). The cardiac event-free survival were 89.1% at 7.2 years in Group A and 26.3% at 8.4 years in Group B (P<0.0001). The Group B had a higher incidence of left ventricular outflow tract obstruction (LVOTO; 3% vs. 33%, P=0.02). The IVS-AV length was found to be a significant risk factor for mortality and LVOTO. The IVS-AV length should, therefore, be taken into consideration when selecting the optimal surgical procedures for these patients.