Context Substantial racial disparities in the use of some health services exist; however, much less is known about racial disparities in the quality of care. Objective To assess racial disparities in the quality of care for enrollees in Medicare managed care health plans. Design and Setting Observational study, using the 1998 Health Plan Employer Data and Information Set (HEDIS), which summarized performance in calendar year 1997 for 4 measures of quality of care (breast cancer screening, eye examinations for patients with diabetes, -blocker use after myocardial infarction, and follow-up after hospitalization for mental illness). Participants A total of 305 574 (7.7%) beneficiaries who were enrolled in Medicare managed care health plans had data for at least 1 of the 4 HEDIS measures and were aged 65 years or older. Main Outcome Measures Rates of breast cancer screening, eye examinations for patients with diabetes, -blocker use after myocardial infarction, and follow-up after hospitalization for mental illness. Results Blacks were less likely than whites to receive breast cancer screening (62.9% vs 70.9%; P<.001), eye examinations for patients with diabetes (43.6% vs 50.4%; P = .02), -blocker medication after myocardial infarction (64.1% vs 73.8%; P<.005), and follow-up after hospitalization for mental illness (33.2 vs 54.0%; P<.001). After adjustment for potential confounding factors, racial disparities were still statistically significant for eye examinations for patients with diabetes, -blocker use after myocardial infarction, and follow-up after hospitalization for mental illness. Conclusion Among Medicare beneficiaries enrolled in managed care health plans, blacks received poorer quality of care than whites.