We examine the relationship between body mass index (weight divided by height squared) and systolic blood pressure and the implications of using obesity as a criterion for blood pressure screening in a multiracial sample of 11,370 schoolchildren. For the entire sample, the zero-order correlation between body mass index and systolic blood pressure was 0.39. Correlations were strongest among Hispanics (r = .51) and weakest among blacks (r = .29). Among white, black, Asian, and Hispanic boys with body mass index values in the upper decile, the odds of having elevated systolic blood pressure (above the 95th percentile) were significantly higher than among individuals in the bottom decile. Among girls with body mass index values in the top decile, higher odds of hypertension were observed only for whites and Hispanics. For the entire population, the sensitivity of screening only children with body mass index values in the top quartile was 52%. The sensitivity of this cutpoint was higher for Hispanics, although 36% of those with elevated systolic blood pressure would still be missed. These data confirm that overweight children are significantly more likely to have elevated systolic blood pressure and total blood cholesterol levels and that weight reduction may play an important role in the primary prevention of coronary heart disease among children of various ethnic backgrounds. Selective screening of overweight children, however, does not appear warranted.