The relationship between blood pressure levels and the risk of cardiovascular diseases has been established for a long time. In recent years, many studies have showed that the risk also depends on the increased blood pressure variability (BPV). BPV is characterized by short-term variability occurring within a 24 hour period (e.g., beat-to-beat, minute-to-minute, hour-to-hour, and day-to-night changes) and also by long-term variability occurring over prolong periods of time (e.g., days, weeks, seasons, and years). Even though some studies have indicated the stabilizing BPV lowers the risk of cardiovascular complication, the clinical implications BPV (especially for long-term BPV) can vary substantially depending on the assessment methods, time interval, and analysis. In this presentation, I will review the pros and cons of methods widely used for BPV assessment. In addition, statistical methods for within-subject long-term BVP data will be also presented.