We report the noninvasive diagnosis of subclavian steal by color-coded Doppler ultrasonography in nine infants with congenital heart disease. The underlying cardiovascular malformations included coarctation of the aorta in four infants, interrupted aortic arch type B in three patients, truncus arteriosus communis type A4 (one patient), and isolation of the right subclavian artery (one patient). In all patients both vertebral arteries could be displayed through the anterior fontanel in coronal sections. Normally the flow in both vertebral arteries, as well as the flow in the basilar artery, is displayed in red. In eight patients with angiographically proved unilateral subclavian steal, an antegrade (red) flow could be shown in one vertebral artery, whereas the contralateral vertebral artery was displayed blue, indicating reverse flow. In one infant with interrupted aortic arch type B and associated aberrant right subclavian artery, both vertebral arteries and the basilar artery were displayed blue, indicating bilateral subclavian steal. Color-coded Doppler sonography seems to be a sensitive, noninvasive method for diagnosing congenital subclavian steal, especially in infants with obstruction of the aortic arch.