Hypertension is an important accelerator of the atherosclerotic process. Detection in childhood may be important although longitudinal data are lacking of the prognosis of blood pressure measurement in childhood through adult life. The blood pressure of children should be measured. In populations where salt intake is high, values for blood pressure increase with age. Populations who eat small quantities of salt are relatively free from hypertension. There is an epidemiological argument for limiting salt intake in children. There are few data to indicate the level of blood pressure in children which should be treated. Children's blood pressures are labile and elevated levels are sustained only in a small minority. In these secondary causes, advice should be sought. In subjects with extreme persistent hypertension drug therapy should be considered; in subjects with values of blood pressure not so extremely raised surveillance should be maintained to prevent the development of sustained hypertension.