BACKGROUND AND OBJECTIVES: The discontinuation of drugs such as angiotensin-converting enzyme inhibitors (ACE inhibitors) has been suggested based on reports of hypotension during anesthesia. This may imply on a higher risk of intraoperative hypertensive peaks with deleterious consequences for the patient. The objective of the present study was to evaluate the influence of the preoperative use of ACE inhibitors on the development of hypotension during anesthesia. METHODS: This is a case-controlled study of patients who developed hypotension after anesthetic induction. The control group was composed of patients of the same age and gender who underwent surgeries during the same period and who did not develop hypotension. Parameters of interest included: age, gender, size of the surgery, prior diagnosis of hypertension, use of ACE inhibitors, physical status (ASA), intraoperative bleeding, anesthetic technique, and duration of the surgery. RESULTS: In 2,179 surgeries, 40 patients developed hypotension. Twenty of those patients used ACEIs on the day of the surgery. The control group was composed by 171 patients, 11 of which used ACE inhibitors. Univariate analysis showed an association between hypertension and advanced age (p < 0.001), prior diagnosis of hypertension (p < 0.001), use of ACEIs (p = 0.006), physical status (ASA) (p = 0.006), and size of the surgery (p = 0.028). Stratified analysis did not show an association between hypotension and use of ACE inhibitors. On logistic regression, the association between the size of the surgery and the age of the patient and the development of hypotension remained. CONCLUSIONS: We did not observe an association between the use of ACE inhibitors and hypotension during anesthesia. The authors considered that the recommendation to discontinue ACE inhibitors on the day before the surgery should be reviewed. Other studies are necessary to confirm those results.