Background: Surgical site infections (SSIs) following vascular surgery have high morbidity and costs, and are increasingly tracked as hospital quality measures. Objective: To assess the ability of Medicare claims to identify US hospitals with high SSI rates after vascular surgery. Research Design: Using claims from fee-for-service Medicare enrollees of age 65 years and older who underwent vascular surgery from 2005 to 2008, we derived hospital rankings using previously validated codes suggestive of SSI, with individuallevel adjustment for age, sex, and comorbidities. We then obtained medical records for validation of SSI from hospitals ranked in the best and worst deciles of performance, and used logistic regression to calculate the risk-adjusted odds of developing an SSI in worst-decile versus best-decile hospitals. Results: Among 203,023 Medicare patients who underwent vascular surgery at 2512 US hospitals, a patient undergoing surgery in a hospital ranked in the worst-performing decile based on claims had 2.5 times higher odds of developing a chart-confirmed SSI relative to a patient with the same age, sex, and comorbidities in a hospital ranked in the best-performing decile (95% confidence interval, 2.0-3.1). SSI confirmation among patients with claims suggesting infection was similar across deciles, and we found similar findings in analyses limited to deep and organ/space SSIs. We report on diagnosis codes with high sensitivity for identifying deep and organ/ space SSI, with one-to-one mapping to ICD-10-CM codes. Conclusions: Claims-based surveillance offers a standardized and objective methodology that can be used to improve SSI surveillance and to validate hospitals' publicly reported data.