Objective: Compare missing data and reliability of health care evaluations between African Americans and Whites in Medicare managed care health plans. Method: Consumer Assessment of Healthcare Providers and Systems (CAHPS) 3.0 health plan survey data collected from 109,980 Medicare managed care enrollees (101,189 Whites, 8,791 African Americans) in 321 plans. Participants self-administered the survey and four single-item global ratings of care. Results: Missing data rates were significantly higher for African Americans than Whites on all CAHPS items (p < .0001). Internal consistency reliability estimates for the CAHPS scales did not differ significantly between African Americans and Whites, but plan-level reliability estimates for the scales and global rating items were significantly lower for African Americans than Whites. Discussion: Higher missing data rates and lower plan-level reliability estimates for African American Medicare managed care enrollees suggest caution in making race/ethnicity comparisons. Future efforts are needed to enhance the quality of data collected from older African Americans. © 2006 Sage Publications.