To determine whether children with white coat hypertension (WCH) have evidence of target-organ damage by comparing the left ventricular mass index (LVMI) of subjects with WCH with that of matched normotensive and hypertensive controls.Each subject in the WCH group was matched by body mass index (BMI; ± 10%), age (± 1 year), and sex to a normotensive control and a hypertensive control. Echocardiograms were reviewed to determine the LVMI for each subject. These triple matches were analyzed using repeated-measures analysis of variance to detect differences in LVMI among the 3 groups.A total of 27 matched triplets were established. The groups were comparable for sex, age, and BMI. Mean LVMI was 29.2 g/m 2.7 for the normotensive group, 32.3 g/m 2.7 for the WCH group, and 35.1 g/m 2.7 for the sustained hypertensive group (normotensive vs WCH, P = .028; WCH vs sustained hypertension, P = .07). Left ventricular hypertrophy was not present in any subject in the normotensive or WCH groups, but was found in 26% of the sustained hypertensive subjects (P < .001).After controlling closely for BMI, the LVMI in the subjects with WCH was between that of the normotensives and sustained hypertensives, suggesting that WCH may be associated with hypertensive end-organ effects.