Mexican Americans have exhibited increases in various coronary heart disease risk factors compared to European Americans but have also had reportedly lower coronary heart disease mortality from vital statistics studies. We hypothesized this apparent paradox might relate to lower levels of subclinical disease in Mexican Americans. A total of 105 adult Mexican Americans (42 men and 63 women, age 46 ± 14 years) and 100 European Americans (59 men and 41 women, age 50 ± 11 years) were studied using blood tests, transthoracic echocardiography, and computed tomography coronary artery calcium (CAC) scans. Despite a greater body mass index and triglycerides in Mexican Americans (p <0.001), the Mexican Americans demonstrated less subclinical disease than did the European Americans (14.4% vs 25.7% with CAC scores >0, p <0.05 and mean left ventricular mass [LV] of 146 vs 160 g, p <0.05). Also, the LV mass was significantly greater in Mexican Americans with than in those without CAC (mean 172 vs 140 g, p <0.05). On logistic regression analysis, age and diastolic blood pressure were associated with an increased likelihood of CAC (p <0.001 and p <0.01, respectively), and Mexican-American ethnicity was associated with a decreased likelihood of CAC (odds ratio 0.33, 95% confidence interval 0.12 to 0.87, p <0.05). On multiple regression analysis, male gender, body surface area, and systolic blood pressure were independently associated with an increased LV mass (all p <0.001). The body mass index was less strongly related to the LV mass than was the body surface area and was not related to CAC. In conclusion, Mexican-American ethnicity is associated with both a lower LV mass and a lower prevalence of CAC, although the differences in LV mass did not remain after adjustment for other factors. Although systolic blood pressure, body surface area, and male gender were most strongly associated with the LV mass, age and diastolic blood pressure, in addition to Mexican-American ethnicity, were the most important indicators of CAC.