Frequency and surgical results of aortic cusp prolapse and aortic regurgitation (AR) associated with ventricular septal defect (VSD) were studied. One hundred thirty-six consecutive patients with type I and II VSD according to Kirklin and associates' classification were divided into two groups; group A included 50 patients with type Ia VSD without the conal muscular rim, and group B included 86 patients with type Ib VSD with the conal muscular rim, or with type II VSD. Aortic cusp prolapse was detected in 74% of group A patients and 29% of group B patients. The aortic cusp prolapse correlated negatively with preoperative left-to-right shunt ratio, mean pulmonary artery pressure, and pulmonary-to-systemic pressure ratio in both groups. In group B patients, the smaller the VSD, the higher the frequency of aortic cusp prolapse, especially when less than 4 mm. Aortic regurgitation was observed in 44% of group A patients and 24% of group B patients. All 20 patients with first grade AR underwent VSD closure, 11 with second or third grade AR underwent VSD closure plus valvuloplasty, and 1 with third grade AR underwent aortic valve replacement. Postoperative persistent AR occurred in 8 out of 32 patients, and correlated positively (p < 0.01) with the preoperative grade of AR and the number of plication stitches in both groups.