This was a population-based observational study to assess the impact of managed care (MC) on several dimensions of quality of surgical care among Medicare beneficiaries undergoing carotid endarterectomies (CEAs) (N = 9308) in New York. Clinical data were abstracted from medical charts to assess appropriateness and deaths or strokes within 30 days of surgery. Differences in patients, appropriateness, and outcomes were compared using chi-square tests; risk-adjusted outcomes were compared using regression. Fee-For-Service (FFS, N = 8691) and MC (N = 897) CEA patients had similar indications for surgery, perioperative risk, and comorbidities. There were no differences in inappropriateness between FFS and MC (8.6% vs 8.4%). MC patients were less likely to use a high-volume surgeon (20.1% vs 13.5%) or hospital (20.5% vs 13.0%, P < .05). There were no differences in risk-adjusted rates of death or stroke (OR = 0.97; 95% CI = 0.69-1.37). Medicare MC plans did not have a positive impact on inappropriateness, referral patterns, or outcomes of CEA.