B lood pressure (BP) is known to be a continuous variable with dynamic characteristics of variability in response to daily physical and mental stimuli. The idea that the variation of BP puts additional burden on the heart and vasculature beyond that of average BP has been regarded for decades as a reasonable concept by researchers, practitioners and even patients. However, in contrast to the straightforward approach required for the evaluation of average BP, the quantification of the BP variability (BPV) turned out to be a tricky task. Interestingly, several different lines of evidence suggest that the BPV has independent prognostic value beyond that of average BP. However, to date the plethora of methodological approaches applied in different studies and the lack of evidence on critical relevant research issues did not allow BPV to be used in practice as a tool for improving the management of hypertensive patients.For the quantification of BPV, several measurement methods and sampling of BP readings have been used, and several mathematical approaches have been applied (Tables 1-2The different methods available for office and out-ofoffice BP measurement have been used to provide information on different aspects of BPV. Evaluation of BPV using each of these methods has been shown to independently predict cardiovascular risk [1-3,11-17]. However, each BPV component seems to reflect different mechanisms, is likely to provide different information on cardiovascular regulation and might have different clinical implications [12,18].Very-short-term BPV can be assessed by continuous beat-to-beat intraarterial BP monitoring or noninvasive finger-cuff photoplethysmography. The use of the former is limited because of the invasive nature and the latter because of questionable measurement accuracy.Short-term BPV is based on intermittent BP sampling at 15-30-min intervals in a routine 24-h period, obtained using noninvasive oscillometric ambulatory monitors. This appears to be an ideal method for routine BPV evaluation, by providing information on the dispersion of BP values in different conditions of posture and activity. However, the independent prognostic value of ambulatory BPV has been questioned, and its application might not be well accepted by patients for repeated use in the long-term management of hypertension. In the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT), ambulatory BPV had less effect on vascular events than that assessed by office measurements [2]. Moreover, analysis of the International Database on Ambulatory Blood Pressure in Relation to Cardiovascular Outcome (IDACO) showed that the 24-h ambulatory BPV did not contribute much to risk stratification over and beyond the average ambulatory BP [15]. It should be mentioned, however, that most of the published studies have been limited by infrequent ambulatory BP sampling, whereas it has been shown that measurements at 15-min intervals are required to provide an accurate assessment of BPV [19].Mid-term day-by-day BPV based on self-home BP monitoring has a...