BACKGROUND: There are few available data on the epidemiology of prehypertension (preHTN). To determine racial, clinical, and demographic differences in the prevalence of preHTN and its cross-sectional association with vascular risk factors. METHODS: Cross-sectional analysis of 5,553 prehypertensives, 20,351 hypertensive's, and 4,246 nonhypertensive participants (age ≥45), from a population-based national cohort study (REasons for Geographic And Racial Differences in Stroke (REGARDS) total population 30,239, of whom 30,150 had adequate blood pressure (BP) measurements) enrolled from January 2003-October 2007 with oversampling from the southeastern stroke belt, and black individuals. Baseline data were collected using a combination of telephone interview and in-home evaluation. preHTN was defined according to The Seventh Report of the Joint national Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) guidelines. RESULTS: The prevalence of preHTN was associated with age and black race (62.9% in blacks compared to 54.1% in whites). A higher prevalence of preHTN was observed in obese individuals, self-reported heart disease; and, those with elevated high-sensitivity C reactive protein (hsCRP), diabetes, and microalbuminuria compared to those without these factors. Heavy alcohol consumption in white participants was associated with increased odds of preHTN (odds ratio (OR) = 1.32) but was even greater in black participants (OR = 2.27). CONCLUSION: The prevalence of preHTN increased by age and African-American race. In addition, a higher prevalence of preHTN was observed with elevated hsCRP, diabetes, microalbuminuria, and those with heavy alcohol consumption compared to those without these factors.