ABSTRACT: Importance:Thirty-five years ago, the Heckler Report described health disparities among minority populations in the US. Since then, policies have been implemented to address these disparities. However, a recent evaluation of progress towards improving the health and health equity among US adults is lacking. Objectives:To evaluate racial/ethnic disparities in the physical and mental health of US adults over the last 2 decades. Design:Cross-sectional. Setting:National Health Interview Survey data, years 1999-2018. Participants:Adults aged 18-85 years. Exposure:Race/ethnicity subgroups (non-Hispanic White, non-Hispanic Black, non-Hispanic Asian, Hispanic). Main outcome and measures:Proportion of adults reporting poor/fair health status, severe psychological distress, functional limitation, and insufficient sleep. We also estimated the gap between non-Hispanic White and the other subgroups for these four outcomes. Results:We included 596,355 adults (mean age 46 years, 51.8% women), of which 69.7%, 13.8%, 11.8% and 4.7% identified as non-Hispanic White, Hispanic, non-Hispanic Black, and non-Hispanic Asian, respectively. Between 1999 and 2018, Black individuals fared worse on most measures of health, with 18.7% (95% CI 17.1-20.4) and 41.1% (95% CI 38.7-43.5) reporting poor/fair health and insufficient sleep in 2018 compared with 11.1% (95% CI 10.5- 11.7) and 31.2% (95% CI 30.3-32.1) among White individuals. Notably, between 1999-2018, there was no significant decrease in the gap in poor/fair health status between White individuals and Black (-0.07% per year, 95% CI -0.16-0.01) and Hispanic (-0.03% per year, 95% CI -0.07- 0.02) individuals, and an increase in the gap in sleep between White individuals and Black (+0.2% per year, 95% CI 0.1-0.4) and Hispanic (+0.3% per year, 95% CI 0.1-0.4) individuals. Additionally, there was no significant decrease in adults reporting poor/fair health status and an increase in adults reporting severe psychological distress, functional limitation, and insufficient sleep. Conclusions and Relevance:The marked racial/ethnic disparities in health of US adults have not improved over the last 20 years. Moreover, the self-perceived health of US adults worsened during this time. These findings highlight the need to re-examine the initiatives seeking to promote health equity and improve health.