In children and adolescents, the diagnosis of hypertension is based on office, home and ambulatory blood pressure (BP) measurements. Different normalcy tables for each method have provided 95th percentiles of BP as thresholds for hypertension diagnosis. This study assessed the differences in BP thresholds among these methods when applied in the pediatric population. The most widely used office, home and ambulatory BP normalcy tables were compared in terms of the 50th and 95th percentiles by gender and age. The range of office BP change with increasing age is wider than for home or ambulatory BP in boys and girls, apart from systolic BP in boys. Percentiles of home BP are consistently lower than that of daytime ambulatory BP. There is a trend for office BP to be lower than home or daytime ambulatory BP in the younger age subgroups. This difference is progressively eliminated with increasing age, apart from systolic BP in boys. In conclusion, in children and adolescents, the relationship between office, home and ambulatory BP thresholds provided by the widely used normalcy tables is not the same as in the adults. These findings should be taken into account when evaluating BP measurements in children and adolescents in clinical practice.