Objective: The aim of this study was to determine the prevalence of abdominal obesity and its impact on the risks of hypertension in the US adult population. Design and methods: Data from the third US National Health and Nutrition Examination Surveys, 1988–1994, were utilised. Abdominal obesity was defined as waist circumference 102 cm in men and 88 cm in women. Hypertension was defined as mean diastolic blood pressure 90 mm Hg, systolic blood pressure 140 mm Hg or current treatment with prescribed hypertension medication. Prevalences of abdominal obesity were estimated in non-Hispanic White, non-Hispanic Black and Hispanic Americans. Gender-specific logistic regression analysis using empirical waist cut-off points was used to determine the risks of hypertension. The impact of abdominal adiposity on risk of hypertension was estimated from population-attributable risk adjusting for age, current smoking and alcohol intake. Results: The prevalences of abdominal obesity were 27.1%, 20.2% and 21.4% in White, Black and Hispanic men, respectively. The corresponding values in women were 43.2%, 56.0% and 55.4%. Abdominal obesity was found to be associated with a two to three-fold increased risk of hypertension in this population. In men, the attributable risk percent ranged from 20.9% in Hispanics to 27.3% in Whites and in women ranged from 36.5% in Whites to 56.5% in Hispanics. We estimated that 24 million adult men and 40 million adult women of Hispanic and non-Hispanic Black and White ethnicity were suffering from abdominal obesity. Conclusions: In this population, hypertension appears to be associated with abdominal obesity. The estimates of population attributable risks suggest that the risk of hypertension could be potentially reduced if waist size were reduced to <102 cm in men and <88 cm in women.