In 167 patients with cerebrovascular disorders 323 carotid bifurcations were investigated by Duplex ultrasound. In 100 of these patients, additionally intravenous digital subtraction angiography (DSA) was performed and in 35 patients, also intra-arterial DSA was carried out. In 32 patients all three procedures were performed. Comparing the results of Duplex scan and intravenous DSA with intra-arterial DSA it can be concluded that Duplex scan and intravenous DSA are comparable as screening methods for the evaluation of haemodynamically relevant stenoses and occlusions in extracranial artery disease. However, for the evaluation of stenotic vessels of less than 50% lumen reduction the Duplex scan showed a higher agreement rate with a contingency coefficient of 0.957 in comparison to intravenous DSA with a contingency coefficient of 0.903.