The recently released Seventh Report of the Joint National Committee (JNC) on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure provides a new classification of blood pressure levels. Little is known about the current situation of elevated blood pressure in the United States, according to the new guidelines. Cross-sectional analysis of national representative data collected from 4805 adults 18 years and older surveyed in the 1999-2000 National Health and Nutrition Examination Survey. We examined the prevalence of prehypertension and hypertension according to the new JNC guidelines, people's awareness and management of hypertension, and the differences across sociodemographic and body weight groups. Elevated blood pressure is a serious problem in the United States. Approximately 60% of American adults have prehypertension or hypertension, and some population groups, such as African Americans, older people, low-socioeconomic-status groups, and overweight groups, are disproportionately affected. The prevalence of hypertension has increased by approximately 10 percentage points during the past decade. The awareness and appropriate management of hypertension among hypertensive patients remain low: 31% were not aware of their disease, only two thirds (66%) were told by health professionals to adopt lifestyle modifications or take drugs to control hypertension, and only 31% controlled their hypertension. With 60% of the population affected, the United States is facing a serious challenge in the prevention and management of prehypertension and hypertension. People's awareness and control of hypertension remain poor. This study highlights the seriousness of the problem and the importance of promoting lifestyle modifications.