['Discontinuation of angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blocker (ARB) medications before surgery has been suggested because of the potentially deleterious effects of hypotension. We investigated the effect of preoperative ACEI and/or ARB use on early outcomes after carotid endarterectomy (CEA).', 'We examined 3752 consecutive CEA patients within the Vascular Study Group of New England from September 2012 to September 2014 and compared outcomes for patients treated (n = 1772) or not treated (n = 1980) with ACEI and/or ARB preoperatively. Outcomes included perioperative need for intravenous vasoactive medication (IVBPmed) for hypotension or hypertension (HTN), major adverse cardiac events (MACEs), and the combined outcome of stroke or death. Adjusted analysis was performed using multivariable logistic regression of the crude cohort and by constructing a propensity score matched cohort (n = 1441).', 'ACEI and/or ARB users were more likely to be male (64% vs 59%; P = .001), with a higher prevalence of diabetes (41% vs 28%; P < .0001), HTN (97% vs 82%; P < .0001), coronary artery disease (31% vs 25%; P = .0001), congestive heart failure (10% vs 8%; P = .02), and asymptomatic carotid disease (59% vs 54%; P = .004). Patients who received ACEI and/or ARB preoperatively were more likely to be treated with aspirin (92% vs 88%; P = .0002) and statins (89% vs 85%; P = .001) preoperatively. In the unadjusted analysis, no significant differences were identified in hypotension that required IVBPmed (12% vs 11%; odds ratio [OR], 1.1; 95% confidence interval [CI], 0.9-1.4; P = .22), MACE (3% vs 2%; OR, 1.3; 95% CI, 0.8-1.9; P = .32), or stroke or death (3% vs 3%; OR, 1.0; 95% CI, 0.7-1.6; P = .89) for preoperative ACEI and/or ARB treated and nontreated patients, respectively. Preoperative ACEI and/or ARB usage was, however, associated with HTN that required IVBPmed (13% vs 10%; OR, 1.3; 95% CI, 1.1-1.6; P = .01). Analysis of the propensity score matched cohort revealed no significant differences in hypotension that required IVBPmed (12% vs 12%; OR, 1.0; 95% CI, 0.8-1.3; P = .86), MACE (3% vs 2%; OR, 1.1; 95% CI, 0.7-1.8; P = .62; ), or stroke or death (3% vs 3%; OR, 1.0; 95% CI, 0.7-1.6; P = .91) for patients treated or not treated with preoperative ACEI and/or ARB, respectively. ACEI and/or ARB remained associated with HTN that required IVBPmed (13% vs 10%; OR, 1.3; 95% CI, 1.0-1.7; P = .02). Results were similar after adjustment using logistic regression. The incidence of hospital length of stay >1 day was similar between ACEI and/or ARB treated and not treated patients (29% vs 32%; OR, 0.9; 95% CI, 0.8-1.1; P = .21).'] Is renin-angiotensin-aldosterone-system inhibition safe in the preoperative period surrounding carotid endarterectomy?