In order to evaluate the outcome of endarterectomy, we estimated the cerebral vasoreactive capacity in 3 main patient groups with carotid artery disease: A. occlusion, B. high-grade, and C. low-grade carotid stenosis. The results showed that certain proportion of patients with reduced CVC can be distinguished in the each investigated groups, indicating thus, those patients in whom endarterectomy can benefit. Our study provides evidence that acetazolamide test with TCD measuring may be used to assess the CVC before and after endarterectomy. Carotid endarterectomy improves CVC in patients who had compromised cerebral perfusion reserve before operation. We suggest that the endarterectomy can also benefit in the patients with carotid occlusion and low grade stenosis if CVC is estimated.