Duplex ultrasound was used to assess the vascular status and predict the angiographic findings in 3 patients with Takayasu's arteritis. The most striking sonographic feature was the presence of concentric arterial wall thickening. Using pulsed Doppler, stenotic lesions were quantified, occlusive lesions were identified and collateral circulation was demonstrated. A high resistive flow pattern was demonstrated in diseased vessels compared with carotid wave-forms of control subjects. Subtle mural irregularity, minor stenotic lesions and areas of stenosis in branch vessels were missed by duplex evaluation. The thoracic aorta and occasionally major arterial branches in the abdomen were impossible to evaluate with ultrasound. Vascular magnetic resonance imaging was successful in delineating major aortic branches but was inferior to real-time ultrasound in resolving mural thickening. While angiography plays a major role as a baseline assessment of the entire vascular tree, duplex ultrasound can monitor disease progression and the effects of therapy. Serial duplex studies should greatly reduce the need for interval angiographic followup.