Systolic blood pressure (SBP) has become the major criterion for the diagnosis, staging, and treatment of hypertension in adults, based on the epidemiology and pathophysiology of adult hypertension, linkage between SBP levels and disease, and benefits of treatment of isolated SBP hypertension. Although children do not typically suffer overt hypertensive disease, an accumulation of data suggests that SBP elevation is as important a factor in the morbidity of hypertension in children as in adults. SBP hypertension is more common in children, whether examining an unselected sample of patients by routine screening or a selected sample of referred hypertensive patients. Mild-to-moderate BP elevation in children is associated with increased left ventricular mass (LVM), with SBP more closely linked to LV morphology than diastolic blood pressure (DBP). Furthermore, SBP is associated with increased LVM even in patients with SBP within the "normal" range. Among hypertensive children, the reported prevalence of LVH ranges from 30% to 70%, and LV hypertrophy is more closely related to SBP than to DBP. These data suggest that treatment of hypertension should be directed at normalization of SBP, even when DBP is within the normal range. In addition, trials of anti-hypertensive medications in children should incorporate SBP hypertension into study inclusion criteria.