Takayasu's arteritis (TA) is a chronic inflammatory disease mainly affecting young females involving the great vessels; the aorta and its major branches. Diagnosis and delineation of patterns of involvement used to depend on intra-arterial angiography in the past. With the advent of high resolution duplex ultrasonographic technique, TA can be non-invasively inspected in the vasculitis phase. Based on our ultrasound study of cervical and lower extremity vessels, 6 patients were proved to have TA by angiography. Some characteristic carotid imaging findings can be identified at the sonographic probe detectable regions, i.e., (1) The inflammatory changes of TA mainly involved the proximal parts of 3 major cervical branches from the aortic arch, but the distal parts of them and the internal carotid arteries are relatively spared. (2) The inflammatory plaques of TA are relatively homogeneous in appearance, concentric in deposition and a long extent of involvement. Differential diagnosis between TA and atherosclerotic changes can be made by the preferential sites, echogenic properties, length of involvement and manner of proliferation. Regular follow-up by ultrasonography in 2 patients showed that response to treatment and disease progression could be easily monitored.