It is not uncommon for patients requiring vascular surgery, and in particular aortic surgery, to have increased requirements for blood transfusion. However, studies examining the effects of perioperative transfusion for thoracic endovascular aortic repair (TEVAR) are limited. Using large multicenter data, we aimed to study the impact of perioperative blood transfusion on 30-day mortality and complications after TEVAR. A total of 9,263 patients who underwent TEVAR were included in this retrospective study from the multicenter Vascular Quality Initiative cohort spanning 2010-2022. We excluded patients who were post-traumatic, anemic (World Health Organization criteria: hemoglobin < 12g/dl and < 13g/dl for females and males respectively), who underwent open conversions or presented with ruptured aneurysms. Primary outcomes were 30-day mortality and stroke. Secondary outcomes were postop congestive heart failure (CHF), respiratory complications, spinal cord ischemia (SCI), myocardial infarction (MI) and any postop complications (composite variable). Poisson regression with robust variance was performed to determine the risk of post op outcomes comparing patients who received red blood cells (RBCs) to those who did not. Comparing patients without any transfusion (n=8,223), perioperative transfusion of 1-3 units (n=735) was associated with 3-fold increased risk of 30-day mortality (adjusted relative risk [aRR] 3.30, 95% confidence interval [CI] 2.39,4.57, P<0.001), almost 2-fold increased risk of stroke (aRR 1.98, 95% CI 1.24,3.15, P=0.004), 2.7-fold increased risk of SCI (aRR 2.66, 95% CI 1.87-3.77, P<0.001), 3-fold increased risk of MI (aRR 3.40, 95% CI 2.30, 5.03, P<0.001), 2-fold increased risk of CHF (aRR 2.04, 95% CI 1.09, 3.83, P=0.03), 3.5-fold increased risk of respiratory complications (aRR 3.49, 95% CI 2.67, 4.56, P<0.001), and 2-fold increased risk of any postop complication (aRR 2.36, 95% CI 2.04, 2.73, P<0.001). These effects were even higher in patients transfused 4 or more units (n=305) than seen in the effects seen in those transfused 1-3 units; comparing each group to patients who received none. In hemodynamically stable patients undergoing TEVAR for nonemergent/emergent and nontraumatic indications, transfusion of any amount perioperatively is associated with worse 30-day mortality, stroke, SCI, MI, CHF, and respiratory complications. A conservative transfusion approach and multidisciplinary care to identify complications and rescue TEVAR patients who receive any amount of RBCs perioperatively might help improve outcomes. Future studies to understand the mechanisms of outcomes for transfused patients are needed.