Objective: Although U.S. mental health treatment rates in-creased in the 2000s, gaps in treatment among racial-ethnic groups grew. Little is known, however, about national trends after 2012, when treatment access increased overall. This study assessed trends in racial-ethnic disparities in past-year treatment rates among people with a major depressive epi -sode, serious psychological distress, or serious mental illness.Methods: National Survey on Drug Use and Health (2005-2019) data of adults with a past-year major depressive episode (N=49,791) or serious psychological distress (N=89,233) and of adults with past-year serious mental illness (N= 24,944; 2008-2019) were analyzed. Linear risk regressions were used to model trends in past-year use of mental health treatment and included an interaction term between survey year and race-ethnicity.Results: Treatment use prevalence (2005-2019) among marginalized individuals with a major depressive episode remained lower than that among White people. The magnitude of the disparity in treatment use between White and Hispanic people with major depressive episode decreased slightly (percentage-point difference=-25.1% to -14.9%), whereas the disparity in treatment use be-tween White people and American Indian/Alaska Native people with serious mental illness increased significantly (percentage-point difference= 23.4% to -12.2%), from 2005 to 2019. The magnitude of the disparities for other marginalized racial-ethnic groups did not meaningfully change.Conclusions: Racial-ethnic disparities in past-year mental health treatment use have persisted. Efforts to reduce dis-parities should consider structural barriers that hinder treatment use among marginalized groups.