Objective: Databases are essential in evaluating surgical outcomes and gauging the implementation of new techniques. However, there are important differences in how data from administrative databases and surgical quality improvement (QI) registries are collected and interpreted. Therefore, we aimed to compare trends, demographics, and outcomes of open and endovascular abdominal aortic aneurysm (AAA) repair in an administrative database and two QI registries. Methods: We identified patients undergoing open and endovascular repair of intact and ruptured AAAs between 2012 and 2015 within the National Inpatient Sample (NIS), the National Surgical Quality Improvement Program (NSQIP), and the Vascular Quality Initiative (VQI). We described the differences and trends in overall AAA repairs for each data set. Moreover, patient demographics, comorbidities, mortality, and complications were compared between the data sets using Pearson χ test.Results: A total of 140,240 NIS patients, 10,898 NSQIP patients, and 26,794 VQI patients were included. Ruptured repairs composed 8.7% of NIS, 11% of NSQIP, and 7.9% of VQI. Endovascular aneurysm repair (EVAR) rates for intact repair (range, 83%-84%) and ruptured repair (range, 51%-59%) were similar in the three databases. In general, rates of comorbidities were lower in NIS than in the QI registries. After intact EVAR, in-hospital mortality rates were similar in all three databases (NIS 0.8%, NSQIP 1.0%, and VQI 0.8%; P = .06). However, after intact open repair and ruptured repair, in-hospital mortality was highest in NIS and lowest in VQI (intact open: NIS 5.4%, NSQIP 4.7%, and VQI 3.5% [P < .001]; ruptured EVAR: NIS 24%, NSQIP 20%, and VQI 16% [P < .001]; ruptured open: NIS 36%, NSQIP 31%, and VQI 26% [P < .001]). After stratification by intact and ruptured presentation and repair strategy, several discrepancies in morbidity rates remained between the databases. Overall, the number of cases in NSQIP represents 7% to 8% of the repairs in NIS, and the number of cases in VQI grew from 12% in 2012 to represent 23% of the national sample in 2015.Conclusions: NIS had the largest number of patients as it represents the nationwide experience and is an essential tool to evaluate trends over time. The lower in-hospital mortality seen in NSQIP and VQI questions the generalizability of the studies that use these QI registries. However, with a growing number of hospitals engaging in granular QI initiatives, these QI registries provide a valuable resource to potentially improve the quality of care provided to all patients.