Moyamoya disease is a progressive cerebrovascular disorder with bilateral occlusion of the basal circulation and development of collateral blood supply. In a 6-month-old female with multifocal ischemic infarctions, transcranial pulsed Doppler sonography revealed extremely high and low cerebral blood flow velocities, dampened waveforms, reversed flow, and musical murmurs. Magnetic resonance angiography revealed different degrees of vascular stenosis and an abnormal collateral network. Moyamoya disease was confirmed by conventional angiography at the age of 10.5 months. Pulsed-wave transcranial Doppler sonography is a noninvasive screening method in infants at risk of moyamoya disease.