OBJECTIVE Surgical treatment of intact thoracoabdominal aortic aneurysm (TAAA) is crucial to prevent rupture but is associated with high perioperative mortality. We tested the hypothesis that provider volume of surgical treatment of TAAA is an important determinant of operative outcome. Patients and methods Clinical information regarding repair of intact TAAA in 1542 patients from 1988 to 1998 was obtained from the Nationwide Inpatient Sample (NIS), a stratified discharge database of a representative 20% of US hospitals. Demographic data included age, sex, race, nature of admission, and comorbid conditions. Annual hospital volume of TAAA treated was grouped into terciles and defined as low (LVH; 1-3 cases [median, 1]), medium (MVH; 2-9 cases [median, 4]), or high (HVH; 5-31 cases [median, 12]). Annual surgeon volume was defined as low (LVS; 1-2 cases [median, 1]) or high (HVS; 3-18 cases [median, 7]). The primary outcome measure was in-hospital postoperative mortality. Secondary outcome measures included length of stay, and cardiac, pulmonary, and renal complications. Adjusted and unadjusted analyses were conducted. RESULTS Overall mortality was 22.3%. Mortality improved over time. LVH and HVH differed in mortality rates (27.4% vs 15.0%; P <.001). Mortality between LVS and HVS also differed significantly (25.6% vs 11.0%; P <.001). When controlling for patient demographic data, comorbid conditions, and postoperative complications, both hospital and surgeon volume were significant predictors of mortality for intact TAAA repair (LVS: odds ratio [OR] 2.6, P <.001; LVH: OR 2.2, P <.001; and MVH: OR 1.7, P =.004). CONCLUSIONS Greater hospital and surgeon TAAA treatment volumes contribute to better outcome. Given the relative high perioperative mortality associated with TAAA repair, regionalization of care to high-volume providers with consistently lower postoperative mortality deserves consideration by patients, physicians, and health care planners.