Left ventricle volume is a factor in determining the type of surgical treatment in patients with a hypoplastic left ventricle. The volume of the hypoplastic left ventricle can be measured by echocardiography and cardiac MRI. In an infant with congenital heart disease and a small left ventricle, cardiac CT was used for this measurement and biventricular repair was performed. The left ventricular end-diastolic volume index showed a gradual increase from 23.2 to 47.9 ml/m(2) 4 months after the biventricular repair, and the postoperative outcome was excellent. Cardiac CT provided an accurate volume of the hypoplastic left ventricle in this infant with congenital heart disease; that volume was used to determine the type of surgical repair.