We investigated the role of low-dose clonidine intravenous (IV) premedication in arterial pressure variation during and after carotid endarterectomy (CEA). A total of 84 patients, American Society of Anesthesiologists (ASA) II-III, scheduled for elective CEA under general anesthesia participated in this study. The patients were divided into 2 groups: group P (n = 42) and group C (n = 42) and received N/S 0.9% (placebo) or clonidine 1 μg/kg IV, respectively, 15 minutes before induction of anesthesia. Recovery times, number of patients needed to be treated for circulatory events (hypertension, hypotension, and bradycardia), number of circulatory events per patient, and consumption of vasoactive drugs (nitroglycerine, phenylphrine, and atropine) intraoperatively and the first 6 hours postoperatively were recorded. Significantly less hypertensive episodes were observed intraoperatively, but more hypotensive episodes were observed postoperatively in patients receiving clonidine. Intravenous premedication with low-dose clonidine (1 μg/kg) seems to be effective in preventing hypertensive episodes during CEA under general anesthesia but seems to increase the incidence of hypotension postoperatively.