White-coat hypertension (WCH) and masked hypertension have been associated with increased cardiovascular risk in adults. In the current study, we investigated: (a) the prevalence of WCH and masked hypertension in pediatric patients and (b) the association of these conditions with target organ damage. A total of 85 children underwent office blood pressure measurements, 24-h ambulatory blood pressure monitoring, echocardiography and ultrasonography of the carotid arteries. Subjects with both office and ambulatory normotension or hypertension were characterized as confirmed normotensives or hypertensives, respectively; WCH was defined as office hypertension with ambulatory normotension and masked hypertension as office normotension and ambulatory hypertension. WCH was found in 12.9% and masked hypertension in 9.4% of the subjects. WCH was significantly more prevalent in obese subjects, while masked hypertension was only present in non-obese ones. Confirmed and masked hypertensives had significantly higher left ventricular mass index than confirmed normotensives (34.0+/-5.8 g/m(2.7), 31.9+/-2.9 g/m(2.7) and 25.3+/-5.6 g/m(2.7), respectively, P<0.05). White-coat hypertensives tended to have higher left ventricular mass index than confirmed normotensives, but the difference was not statistically significant (27.8+/-5.1 g/m(2.7) versus 25.3+/-5.6 g/m(2.7)). No significant differences were found in the intima-media thickness of the carotid arteries between confirmed normotensives, white-coat hypertensives, masked hypertensives and confirmed hypertensives. WCH and masked hypertension are common conditions in children. Confirmed and masked hypertension in pediatric patients are accompanied by increased left ventricular mass index.