DATA ARE PRESENTED for 933 Hispanic and 7087 white men and women, ages 25 to 74, who participated in biennial cross-sectional surveys in California from 1979 to 1990. Using an unadjusted analysis, white women and men had significantly higher mean systolic blood pressures (123.4 mmHg versus 119.6 mmHg) and higher levels of hypertension (29.0% versus 22.9%) than Hispanic women and men (P values greater than 0.001). To reduce bias from confounding, a subset of 702 Hispanics were matched to 702 whites on age, gender, education, city of residence, and time of survey. All ethnic differences in blood pressure became nonsignificant in this analysis. The mean systolic blood pressure for whites was 120.0 mmHg; for Hispanics, 120.7 mmHg (24.4% hypertension for both groups, P values greater than 0.10). These findings show the importance of taking sociodemographic factors into account when examining ethnic differences in blood pressure.