Large differences in blood pressure (BP) by ethnic group are apparent among adults. There is uncertainty as to whether similar differences by ethnic group exist among children and, if so, the age of onset. BP measurements were obtained from 58 698 children at 78 556 visits using Pediatric Task Force data, a collection of 11 studies with BP data from children and adolescents age 1 to 17 years. Generalized estimating equation methods were used to identify sex-specific differences in body mass index (BMI)-adjusted rates of BP elevation and prehypertension by ethnic group. Significant BMI-adjusted differences in rates of BP elevation were found between Hispanic boys versus white boys (odds ratio: 1.21; 95% CI: 1.07 to 1.37; P=0.002). No overall significant differences were found between black boys versus white boys (odds ratio: 1.03; 95% CI: 0.95 to 1.12; P=0.49); however, there was significant effect modification (P=0.01) with significant differences found for normal-weight boys (BMI: <85th percentile; OR black versus white: 1.14; 95% CI: 1.03 to 1.27; P=0.01) but not for overweight boys (BMI: > or =85th percentile; OR black versus white: 0.90; 95% CI: 0.78 to 1.05; P=0.20). No overall ethnic group differences in BMI-adjusted rates of hypertension were found for girls. Ethnic differences in prevalence rates of pediatric BP elevation that are not explained by obesity are present, primarily in boys. Whether these differences are attributable to genetic or environmental factors is unknown.