The availability of new technologies that enable blood pressure to be measured and re corded continuously or repetitively during prolonged observation periods has created ex citing opportunities for studying the physiology of blood pressure regulation and the characteristics of clinical hypertension. Ambulatory blood pressure monitoring has been based on three types of approach. The first of these has utilized an intra-arterial catheter that allows blood pressure to be meas ured directly and continuously during a full 24-hour period. The second approach is based on non-invasive techniques,...