Background: Minorities&rsquo / diminished returns (MDRs) refer to systemically weaker effects of socioeconomic status (SES), particularly educational attainment, on the health of non-Whites compared to Whites. Aim: Using a nationally representative sample, we aimed to investigate ethnic differences in the effect of SES (educational attainment) on the self-rated oral health of Hispanic older adults in the US. Methods: This study analyzed the University of Michigan National Poll on Healthy Aging (UM-NPHA) 2017 data, which included 2131 older adults who were 50 to 80 years old (202 Hispanics and 1929 non-Hispanics). Ethnicity, race, educational attainment (SES), age, gender, employment, retirement, and self-rated oral health (single item) were measured. Logistic regressions were applied for data analysis. Results: High educational attainment was associated with lower odds of poor oral health in the pooled sample, net of all covariates. The effect of educational attainment on poor self-rated oral health was found to be weaker for Hispanics than for non-Hispanics. Conclusion: We observed MDRs of educational attainment (SES) on oral health for Hispanic older adults. In other words, compared to non-Hispanics, Hispanics gain less oral health from their educational attainment (SES).