To characterize the distribution of blood pressure (BP), prevalence, and risk factors for hypertension in pediatric chronic kidney disease, we conducted a cross-sectional analysis of baseline BPs in 432 children (mean age 11 years; 60% male; mean glomerular filtration rate 44 mL/min per 1.73 m(2)) enrolled in the Chronic Kidney Disease in Children cohort study. BPs were obtained using an aneroid sphygmomanometer. Glomerular filtration rate was measured by iohexol disappearance. Elevated BP was defined as BP >or=90th percentile for age, gender, and height. Hypertension was defined as BP >or=95th percentile or as self-reported hypertension plus current treatment with antihypertensive medications. For systolic BP, 14% were hypertensive and 11% were prehypertensive (BP 90th to 95th percentile); 68% of subjects with elevated systolic BP were taking antihypertensive medications. For diastolic BP, 14% were hypertensive and 9% were prehypertensive; 53% of subjects with elevated diastolic BP were taking antihypertensive medications. Fifty-four percent of subjects had either systolic or diastolic BP >or=95th percentile or a history of hypertension plus current antihypertensive use. Characteristics associated with elevated BP included black race, shorter duration of chronic kidney disease, absence of antihypertensive medication use, and elevated serum potassium. Among subjects receiving antihypertensive treatment, uncontrolled BP was associated with male sex, shorter chronic kidney disease duration, and absence of angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use. Thirty-seven percent of children with chronic kidney disease had either elevated systolic or diastolic BP, and 39% of these were not receiving antihypertensives, indicating that hypertension in pediatric chronic kidney disease may be frequently under- or even untreated. Treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers may improve BP control in these patients.