A literature overview is given of the characteristics of 24-hour ambulatory blood pressure monitoring (ABPM) and its usefulness in the diagnosis of early hypertension. Ambulatory blood pressure monitoring is well established in adults and is becoming increasingly common in children and adolescents. ABPM is a particularly suitable method of estimating the 24-hour blood pressure profile in children and adolescents with occasional hypertension. ABPM reduces measurement error, is relatively easy to use, and yields far more blood pressure parameters compared with clinical blood pressure measurements. Researchers have used ABPM to study normal blood pressure patterns, “white coat effect” on blood pressure, and characteristics of the blood pressure profile in children with renal diseases and diabetes.