Ambulatory and home blood pressure (BP) measurements more accurately and reliably reflect the true BP levels of individuals than conventional BP measurement. Moreover, they can be measured over an extended period, thus generating information about BP variability. We conducted a population-based prospective study in Japan (the Ohasama study), demonstrating their superior predictive power for cardiovascular mortality/morbidity over conventional BP measurements as well as unique prognostic significance of variability in their values. Masked hypertension defined as normal conventional BP and high ambulatory or home BP was associated with worse prognosis. A disturbed nocturnal decline in BP was associated with cerebral infarction and heart diseases, whereas a large morning surge in BP was associated with cerebral hemorrhage. Morning hypertension at home, a reflection of a disturbed nocturnal decline or a large morning surge in BP, was a good predictor of stroke, particularly among individuals using anti-hypertensive medication. The J-HOME (Japan Home versus Office Measurement Evaluation) study among hypertensive patients receiving antihypertensive treatment revealed that morning home BP levels were not adequately controlled among approximately 60% of the patients. Interim analysis of the HOMED-BP (Hypertension Objective treatment based on Measurement by Electrical Devices of Blood Pressure) study, a randomized controlled trial to determine optimal target of morning home BP, demonstrated effectiveness of systematic antihypertensive drug regimen to lower morning home BP levels. The diagnosis and treatment of hypertension can be managed effectively by considering information from home and ambulatory BP monitoring.