Higher self-reported rumination, a common form of trait perseverative cognition, is linked with lower resting heart rate variability (HRV), which indicates poorer cardiac function and greater disease risk. A prior meta-analysis and systematic review indicates that in samples with fewer European Americans, the association of rumination with both heart rate and blood pressure was stronger. Thus, trait rumination may be more strongly associated with HRV among ethnically minoritized populations, but few studies exist. The current study therefore investigated whether differences in the association of self-reported rumination with resting HRV varied by ethnicity in a sample (N = 513; Mage = 19.41; 226 Women) of self-identified African Americans (n = 110), Asian Americans (n = 84), and European Americans (n = 319). Participants completed a 5-min baseline period to assess resting HRV, followed by the Ruminative Responses Scale, which contains three facets of rumination including brooding, depressive, and reflective rumination. On average, Asian Americans reported higher levels of rumination relative to European Americans. African Americans had higher average HRV than Asian Americans. Adjusting for covariates, higher self-reported rumination was significantly associated with lower HRV in both African and Asian Americans, but not significantly so in European Americans. This finding was consistent for brooding and reflective, but not depressive rumination. Overall, this study lends insight into a psychological mechanism – rumination – that may impact health disparities among ethnically minoritized individuals, contributing to an understanding of how stress gets under the skin among such populations.