High blood pressure (HBP) increases the risk for heart disease and stroke, the first and third leading causes of death in the United States, respectively. An estimated one in four U.S. adults has HBP, which is defined as taking antihypertensive medication or having either a systolic blood pressure (SBP) of > or = 140 mmHg or a diastolic blood pressure (DBP) of > or = 90 mmHg. Optimal blood pressure is defined as SBP of < or = 120 mmHg or DBP of < or = 80 mmHg. To reduce the prevalence of HBP in the United States, the National Heart, Lung, and Blood Institute initiated the National High Blood Pressure Education Program (NHBPEP) in 1972, recommending that all adults aged > or = 20 years have their blood pressure (BP) checked at least once every 2 years. Although HBP is easily detectable and can usually be controlled with treatment, greater awareness of BP levels among U.S. adults is needed. This report summarizes data from the Behavioral Risk Factor Surveillance System (BRFSS) on state-specific trends in recent BP screening and prevalence of HBP (both by self-report). The findings indicate that during 1991-1999, BP screening levels were very high, and the percent of adults reporting HBP increased among some populations. Innovative education and intervention programs are needed to prevent and treat HBP in five high-risk groups: men, blacks, Hispanics, persons with less education, and older adults.