Blood pressure fluctuations appear more significant in patients with poorly controlled hypertension and are known to be associated with adverse perioperative morbidity. In the present study, we aimed to determine the effects of antihypertensive drug treatment strategies on preanesthetic operating room blood pressure measurements. Methods: A total of 717 patients participated in our study; 383 patients who were normotensive based on baseline measurements and not under antihypertensive therapy were excluded from the analysis. The remaining 334 patients were divided into six groups according to the antihypertensive drug treatment. These six groups were examined in terms of preoperative baseline and pre-anesthesia blood pressure measurements. Results: As a result of the study, it was observed that 24% of patients had high blood pressure precluding surgery, and patients using renin-angiotensin-aldosterone system inhibitors (RAASI) had higher pre-anesthesia systolic blood pressure than patients using other antihypertensive drugs. Patients who received beta-blockers were also observed to have the lowest pre-anesthesia systolic blood pressure, diastolic blood pressure, and mean blood pressure, compared to others. Conclusions: Recently, whether RAASI should be continued preoperatively remains controversial. Our study shows that RAASI cannot provide optimal pre-anesthesia blood pressure and lead to an increase in the number of postponed surgeries, probably due to withdrawal of medication before the operation. Therefore, the preoperative discontinuation of RAASI should be reevaluated in future studies.