During the past 15 years several paradigms to study dynamic cerebral autoregulation (CA) were developed by measuring cerebral blood flow (CBF) velocity with transcranial Doppler (TCD) in response to blood pressure changes. As a more indirect approach to measure autoregulation, vasomotor reactivity (VMR) can be determined by the use of vasodilatory stimuli. CA or VMR are often severely disturbed in occlusive carotid artery disease. Several prospective studies have shown that reduced VMR is an important risk factor for stroke or TIA in patients with symptomatic and asymptomatic carotid artery stenosis or occlusion. Future randomized intervention studies will show whether asymptomatic patients with carotid artery stenosis and pathological autoregulation or VMR will benefit from revascularization therapy.