Studies have documented ethnic differences in advance directive (AD) completion, with lower rates in minority groups. Of those with ADs, blacks are more likely than whites to prefer aggressive care, but little is known about how these differences in preferences have changed over time in ethnic groups. This nationally representative study aimed to investigate whether these differences in AD development persisted after adjusting for important confounding variables. Year of death was analyzed to see how AD completion changed over time within ethnic groups, and for those with an AD, the association between these factors and opting for aggressive care was investigated. Data from the 2000 to 2012 Health and Retirement Study (HRS) exit interviews from 7,177 decedents were used. Analyses included logistic regression to determine the relationship between ethnicity and AD completion and preferences for aggressive care and how it changed over time in ethnic groups. Forty-six percent of decedents had completed an AD (whites 51.7%, Hispanics 18.0%, blacks 15.0%). Of blacks completing an AD, 23.8% elected prolonged care, compared with 13.3% of Hispanics and 3.3% of whites. Logistic regression revealed that blacks 75% lower odds of completing an AD and Hispanics had 70% lower odds. Model covariates had a small influence on ethnic differences, although in examining the change in AD completion over time, the odds of having an AD increased with each subsequent death year for blacks and whites but not Hispanics. Additional research is needed to investigate the effect of cultural differences in AD completion rates of ethnic minority groups to ensure that preferences are honored in the clinical setting.