Office and out-of-office blood pressure measurements are being used for the diagnosis of hypertension in children and adolescents. The US National Heart, Lung, and Blood Institute have recently presented a new classification of blood pressure. On the basis of office measurements the 90th, 95th and 99th percentile for gender, age and height are used to classify children and adolescents as normotensive, pre-hypertensive and stage-1 or stage-2 hypertensive. Although auscultation using a standard mercury sphygmomanometer remains the recommended method, accumulating evidence suggests that ambulatory blood pressure monitoring is useful for the detection of white-coat hypertension and the prediction of target organ damage in children and adolescents. Studies have shown ambulatory blood pressure to be more reproducible than office measurements and normative tables for ambulatory measurements have been developed from cross-sectional studies in children and adolescents. In regard to home measurements in children, there are limited data from small trials showing lower blood pressure levels than daytime ambulatory blood pressure. In conclusion, ambulatory blood pressure monitoring is already finding a role as a supplementary source of information in children and adolescents, whereas at present home measurements should not be used for decision making in this population.