Coronary artery bypass is increasingly used as a revascularization procedure to treat pediatric coronary artery problems. We report here the clinical usefulness of high resolution computed tomographic scan in the evaluation of the internal mammary artery bypass graft in a 12-year-old child who had undergone arterial switch operation for transposition of the great arteries. Our case suggests the following practice already applied in our institution: 64-slice computed tomography can be used as a valuable noninvasive diagnostic and screening tool for detecting coronary and artery bypass graft complications in the follow-up of the arterial switch operation before having recourse to conventional angiography.