BACKGROUND: This study's purpose was to assess whether larger volumes of reinfused unwashed shed autologous blood (SAB) were associated with adverse events within 30 days for patients undergoing open thoracoabdominal aortic aneurysm (TAAA) repair. During TAAA repair, our institution uses a system wherein SAB is filtered, but not washed or centrifuged, and then returned to the patient via a rapid-infusion device. By reinfusing SAB, the system preserves the patient's autologous whole blood and may reduce the number of allogenic transfusions required during TAAA repair, but the end-organ effects of reinfusing unwashed SAB have not been extensively evaluated. METHODS: Using a prospectively maintained database, we retrospectively analyzed data from 972 consecutive patients who underwent open TAAA repair at our institution from 2007 to 2021 and who received SAB. Multivariable logistic regressions were performed to assess whether SAB reinfusion volume was associated with a composite outcome of adverse events, as well as operative mortality, a composite of cardiac complications, a composite of pulmonary complications, or persistent paraplegia, stroke, or postoperative renal failure. RESULTS: Among the cohort of 972 patients, the median volume of reinfused SAB was 4159 mL (quartile1-quartile3 [Q1-Q3]: 2524-6790 mL). Greater reinfusion volumes of unwashed SAB were not associated with greater odds of composite adverse events (odds ratio [OR], 1.02 per 1000 mL increase, 97.5% confidence interval [CI], 0.94-1.09, P = .624), nor with any individual outcome-operative mortality (OR, 1.02 per 1000 mL increase, 97.5% CI, 0.93-1.12, P = .617), a composite of cardiac complications (OR, 0.98 per 1000 mL increase, 97.5% CI, 0.93-1.04, P = .447), a composite of pulmonary complications (OR, 1.00 per 1000 mL increase, 97.5% CI, 0.94-1.06, P = .963), renal failure necessitating hemodialysis (OR, 1.01 per 1000 mL increase, 97.5% CI, 0.92-1.11, P = .821), persistent paraplegia (OR, 0.97 per 1000 mL increase, 97.5% CI, 0.84-1.13, P = .676), persistent stroke (OR, 0.85 per 1000 mL increase, 97.5% CI, 0.70-1.04, P = .070), or reoperation to control bleeding (OR, 0.99, 97.5% CI, 0.87-1.13, P = .900)-when adjusted for confounders. CONCLUSIONS: For patients undergoing open TAAA repair, larger reinfusion volumes of unwashed SAB were not associated with greater odds of major early postoperative complications.