Non-invasive ambulatory blood pressure monitoring is increasingly being used in the diagnosis and the treatment of adult hypertensive patients. In children, the most obvious clinical use for intermittent blood pressure recordings is in the evaluation of borderline hypertension and the assessment of the efficacy of antihypertensive therapy. Adolescents who are hypertensive in the presence of the doctor are more often normotensive outside the physician's office than adult and elderly patients. Many elderly patients with isolated systolic hypertension have normal ambulatory systolic readings. Elderly patients with high blood pressures only in the physician's presence generally do not show a fall in ambulatory blood pressures when antihypertensive therapy is initiated or intensified. Thus, ambulatory blood pressure monitoring may be useful in detecting truly hypertensive patients among children and adolescents and in elderly people. This technique should make it possible to better define the cardiovascular risk, to avoid overtreatment and to individualize antihypertensive therapy.