A 36-year-old Italian woman with active Takayasu's disease presented a bilateral occlusions of subclavian artery and stenosis of bilateral common carotid arteries: the maximal diameter stenosis, measured with echo-Doppler color-flow (EDCF) in the longitudinal section was of 43.5 +/- 2.4% on the right and 61 +/- 1.4% on the left. Prednisolone was administered for 30 months at doses from 25 to 6 mg daily (12.5 mg every two days). During steroid therapy we could monitor by EDCF the anatomic change of the involved vessel and a final decrease in carotid wall thickening of 19.8% on the left and 14.0% on the right side. This work demonstrates for the first time that duplex sonography may be an useful tool to asses possible anatomic changes in the carotid lesions of Takayasu's arteritis in response to steroid therapy.