BACKGROUND Blood pressure levels and the prevalence of hypertension are related to adiposity. We evaluated the relationship of adiposity to blood pressure in normotensive and untreated hypertensive African Americans-an ethnic group with a high prevalence of hypertension and obesity. METHODS Outpatient measurements were obtained in 1,858 normotensive and 1,998 hypertensive subjects (44% untreated) residing in Milwaukee. The blood pressure-adiposity relationship was also analyzed in non-Hispanic black (n = 908) and non-Hispanic white (n = 2182) National Health and Nutrition Examination Survey (NHANES) participants. RESULTS In Milwaukee subjects, body mass index (BMI), waist/hip ratio, waist/height ratio, and percent body fat were higher in hypertensives (P < 0.0001). Combining normotensive and untreated hypertensive subjects, each of the anthropometric indices was correlated with systolic and diastolic blood pressure (P <0.0001). In separate analyses, correlations of the indices with blood pressure were observed in normotensive subjects (P < 0.0001), but generally not in hypertensive subjects. Further, separating all subjects into quartiles based on systolic blood pressure, indices of adiposity correlated with blood pressure only in subjects in the lowest blood pressure quartile (blood pressure <120/78 mm Hg). Similarly, among NHANES participants, blood pressure correlated with anthropometric indices in normotensive (P < 0.0005), but not in untreated hypertensive blacks or whites. CONCLUSIONS Although indices of adiposity were greater in hypertensive than in normotensive subjects, blood pressures were significantly correlated with measures of adiposity in normotensive, but not in untreated hypertensive subjects. We hypothesize that the blood pressure-adiposity relationship in hypertensives is modulated by a combination of environmental and genetic factors.