Ambulatory blood pressure monitoring is a useful procedure in the diagnosis and management of hypertension, in the assessment of anti-hypertensive drugs and as a means of predicting outcome in hypertension. With ambulatory blood pressure monitoring is possible to detect usual variability of blood pressure, circadian rhythms and the response to environmental influences in both normotensive and hypertensive subjects. A number of clinical conditions are better evaluated with this procedure than with conventional measurements, eg white-coat hypertension (the rise of blood pressure in the physician's office), borderline hypertension, episodic hypertension and secondary hypertension. Multiple readings improve the precision of the estimate of blood pressure profile of the patient and allow a precise evaluation of blood pressure load to which a patient is exposed throughout 24 h. Ambulatory blood pressure monitoring is closely related to the incidence of cardio- and cerebrovascular events and to the prevalence and the degree of target-organ damage. Casual and ambulatory blood pressure readings are not alternative but complementary tools for clinical management of hypertension and for assessment of the prognostic risk of hypertension.