Splenectomy is often performed during open thoracoabdominal aortic aneurysm (TAAA) repair, because capsular tears are common and can be associated with significant bleeding. It is unknown whether splenectomy affects the short- or long-term outcomes after TAAA repair. All open type I to IV TAAA repairs performed from 1987 to June 2015 were evaluated using a single institutional database. The primary endpoints were in-hospital death, major adverse events (MAE) and long-term survival. The secondary endpoint was hospital length of stay (LOS). All repairs performed for aneurysm rupture were excluded. Univariate analysis was conducted using the Fisher's exact test for categorical variables and the Wilcoxon rank sum test for continuous variables. Logistic and linear multivariable regression were used for the in-hospital endpoints, and survival analyses were performed using Cox proportional hazards modeling and Kaplan-Meier techniques. A total of 649 patients met the study inclusion criteria. Of the 649 patients, 150 (23%) underwent concurrent splenectomy (CS) and six required emergency splenectomy secondary to bleeding postoperatively, leading to 156 cases of total in-hospital splenectomy. The perioperative mortality rate was 5.2% in the CS group and 5.2% in the non-CS group (P = 1.0). MAE were experienced by 48% of the CS patients compared with 34% of the non-CS patients (P = .003). Multivariable analysis revealed splenectomy was not independently predictive of perioperative death (adjusted odds ratio, 0.95; 95% confidence interval [CI], 0.41-2.23; P = .9). However, splenectomy was independently associated with any MAE (adjusted odds ratio, 1.78; 95% CI, 1.19-2.65; P = .005). Splenectomy was also associated with a longer length of stay (+5.39 days; 95% CI, 1.86-8.92; P = .003). No survival difference was found between the cohorts in the total splenectomy cohort in the unadjusted (log-rank P = 1.0) or adjusted (splenectomy adjusted hazard ratio, 1.02; 95% confidence interval, 0.78-1.35; P = .9). CS during open TAAA repair did not lead to increased perioperative mortality but did lead to significantly increased perioperative morbidity and longer hospital lengths of stay. We found no difference in long-term survival outcomes when CS was performed. Splenectomy during TAAA repair did not affect long-term survival. Copyright © 2021 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.