This study determined potential racial and ethnic disparities in risk for all-cause 30-day readmission among traditional Medicare (TM) and Medicare Advantage (MA) beneficiaries initially hospitalized for acute myocardial infarction, congestive heart failure, or pneumonia. Our analyses of New York State hospital administrative data between 2009 and 2012 found that overall 30-day readmission rate declined from 22.0% in 2009 to 20.7% in 2012 for TM beneficiaries, and from 20.2% in 2009 to 17.9% in 2012 for MA beneficiaries. However, persistent racial disparities were found in propensity-score–based analyses among TM beneficiaries (e.g., in 2012, adjusted odds ratio [OR] = 1.11, 95% confidence interval [CI] = 1.01-1.23, p = .029), though not among MA beneficiaries (in 2012, adjusted OR = 1.05, 95% CI = 0.92-1.19, p = .476). We did not find evidence of persistent ethnic disparity for TM (in 2012, adjusted OR = 1.08, 95% CI = 0.93-1.25, p = .303) or MA (in 2012, adjusted OR = 0.99, 95% CI = 0.88-1.11, p = .837) beneficiaries. We conclude that enrollment in MA seemed to be associated with significantly reduced readmission rate and potentially reduced racial disparity.