Background-: Mexican-Americans (MA) exhibit increases in various cardiovascular disease (CVD) risk factors compared to non-Hispanic Whites (NHW), yet are reported to have lower CVD mortality rates. Our aim was to help explain this apparent paradox by evaluating endothelial function and urine albumin levels in MA and NHW. Methods-: One hundred-five MA and 100 NHW adults were studied by brachial artery flow-mediated dilatation (FMD), blood and urine tests. Participants were studied by ultrasounddetermined brachial artery flow-mediated dilatation (FMD), blood and urine tests, at a single visit. Results-: Despite higher BMI and triglycerides in MA, MA demonstrated higher FMD than did NHW (9.1 +/- 7.3% vs. 7.1 +/- 6.3%, p < 0.04). Among MA, urinary albumin was consistently lower in participants with FMD = 7% FMD versus < 7% FMD (p < 0.006). In multivariate analyses in MA men, urinary albumin was inversely related to FMD (r = -0.26, p < 0.05), as were BMI and systolic blood pressure. In MA women, urinary albumin: creatinine ratio was an independent inverse predictor of FMD (p < 0.05). Conclusion-: To our knowledge, this is the first study to analyze, in asymptomatic adults, the relation of MA and NHW ethnicity to FMD and urine albumin levels. The findings confirm ethnic differences in these important subclinical CVD measures.