Background Surgical repair of abdominal aortic aneurysms (AAA) is increasingly being performed, but little is known about the correlates of in-hospital cost associated with this procedure. Methods and Results Baseline clinical characteristics, in-hospital outcomes, and total in-hospital costs were examined among a retrospective cohort of 71 patients who underwent AAA repair. Median age was 68 years, and 75% of the patients were men. High-risk characteristics for perioperative complications were common and included hypertension (73%), documented coronary artery disease (66%), smoking (60%), previous myocardial infarction (47%), history of congestive heart failure (12%), urgent or emergent AAA repair (16%), and diabetes mellitus (11%). Perioperative complications included congestive heart failure (13%), myocardial infarction (11%), and death (1%). Median length of stay in the surgical intensive care unit (SICU) was 2 days (range 0 to 28), and median in-hospital stay was 9 days (range 5 to 39). In-hospital cost for the 71 patients ranged from $13,766 to $82,435 (mean $25,931, median $21,633). Univariate and multiple linear regression analyses demonstrated that among the potential correlates investigated, number of SICU days (P = .007) and total length of stay (P < .0001) were the most closely associated with in-hospital cost. Conclusions Among patients undergoing AAA repair, the major correlates of in-hospital cost are the number of days spent in the SICU and the total number of days spent in the hospital. These results suggest that any intervention that reduces length of stay may significantly reduce the total in-hospital cost associated with AAA repair. (Am Heart J 1998;136:696-702.)