BACKGROUND: Elevated blood pressure (BP) is the largest contributing risk factor to all-cause and cardiovascular mortality. PURPOSE: To update a systematic review on the benefits and harms of screening for high BP in adults and to summarize evidence on rescreening intervals and diagnostic and predictive accuracy of different BP methods for cardiovascular events. DATA SOURCES: Selected databases searched through 24 February 2014. STUDY SELECTION: Fair- and good-quality trials and diagnostic accuracy and cohort studies conducted in adults and published in English. DATA EXTRACTION: One investigator abstracted data, and a second checked for accuracy. Study quality was dual-reviewed. DATA SYNTHESIS: Ambulatory BP monitoring (ABPM) predicted long-term cardiovascular outcomes independently of office BP (hazard ratio range, 1.28 to 1.40, in 11 studies). Across 27 studies, 35% to 95% of persons with an elevated BP at screening remained hypertensive after nonoffice confirmatory testing. Cardiovascular outcomes in persons who were normotensive after confirmatory testing (isolated clinic hypertension) were similar to outcomes in those who were normotensive at screening. In 40 studies, hypertension incidence after rescreening varied considerably at each yearly interval up to 6 years. Intrastudy comparisons showed at least 2-fold higher incidence in older adults, those with high-normal BP, overweight and obese persons, and African Americans. LIMITATION: Few diagnostic accuracy studies of office BP methods and protocols in untreated adults. CONCLUSION: Evidence supports ABPM as the reference standard for confirming elevated office BP screening results to avoid misdiagnosis and overtreatment of persons with isolated clinic hypertension. Persons with BP in the high-normal range, older persons, those with an above-normal body mass index, and African Americans are at higher risk for hypertension on rescreening within 6 years than are persons without these risk factors. PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality.