The aim of the study was to examine how blood pressure is affected by carotid endarterectomy over a 2-year period. We analyzed the data from 997 patients who received best medical care alone and 999 patients who received best medical care plus carotid endarterectomy (CE). All patients were recruited by the North American Symptomatic Carotid Endarterectomy Trial and were followed at regular clinic visits. The mean blood pressure at baseline was 145.2/81.2 mm Hg for medically treated patients and 146.2/81.9 mm Hg for surgically treated patients. The mean systolic and diastolic pressures increased by approximately 2.5% in the first month following randomization, then decreased over the next year and then remained relatively uniform. Throughout follow-up, surgical patients had slightly higher blood pressures than medically treated patients. At the end of 2 years, the mean systolic pressures in the two treatment groups converged to 147.6 mm Hg. The mean diastolic pressure in the medical patients returned to its baseline value, whereas the surgical patients' blood pressure remained slightly elevated by 0.5 mm Hg. The percentage of patients on antihypertensive medications mirrored the rise and fall in blood pressures. A sharp decrease in medication (from 56 to 43%) was observed in both treatment groups at 1 month. The percentage of patients on medication increased subsequently, with approximately 63% taking medication at the end of 2 years. CE does not affect long-term blood pressure. The use of antihypertensive medications appears to be the key component in blood pressure management. As hypertension is related to neurologic morbidity and mortality, strict regulation of blood pressure is extremely important in patients with cerebrovascular disease.