Nine patients with histologically confirmed Horton's diseases were explored by Doppler ultrasound examination, before and after corticotherapy, of the cervical arteries, temporal arteries (N = 9), and branches of the ophthalmic artery: internal nasal (N = 9), central retinal, and supraorbital (N = 6). Excellent correlations existed between histological findings and results of Doppler examination, concerning the severity of the lesions (80% correlation). Circulatory slowing was evident in the ophthalmic vessels studied, with alterations in the shape of peak velocities in 6 of the 9 cases. Major abnormalities were present in 3 patients; two of them presenting transient or permanent amaurosis. Doppler curves improved after corticotherapy, their shape and amplitude becoming equivalent to those of a control population of the same age. Doppler examinations appear to be of diagnostic value in Horton's disease, as well as being able to predict the risk of ophthalmological complications; more effective surveillance of corticotherapy is possible.