Background: Uncontrolled hypertension is the most common and important risk factor for cardiovascular and renal disease. We studied factors associated with hypertension control in the Third National Health and Nutrition Examination Survey. Methods: A total of 3077 non-Hispanic whites, 1742 non-Hispanic blacks, and 1067 Mexican Americans 18 years or older with hypertension were included in the current analysis. Blood pressure was measured by trained observers by means of a standard mercury sphygmomanometer, and controlled hypertension was defined as a mean systolic/diastolic blood pressure less than 140/90 mm Hg. Results: Percentages of persons with controlled hypertension differed significantly by ethnicity and sex: 19.2% and 28.7% for white men and women, 17.5% and 28.6% for black men and women, and 12.7% and 18.0% for Mexican American men and women, respectively. After adjustment for important covariables, percentages of persons with controlled hypertension were significantly higher among persons who were currently (odds ratio [OR] 2.39; 95% confidence interval [CI], 1.52-3.74) or formerly (OR, 1.81; 95% CI, 1.12-2.93) married, had private health insurance (OR, 1.59; 95% CI, 1.02-2.49), visited the same facility for their health care (OR, 2.77; 95% CI, 1.88-4.09) or saw the same provider for their health care (OR, 2.29; 95% CI, 1.74-3.02), had their blood pressure checked during the preceding 6 months (OR, 8.00; 95% CI, 3.75-17.1) or 6 to 11 months (OR, 5.31; 2.51-11.2), and reported using lifestyle modification to control their hypertension (OR, 6.02; 95% CI, 4.20-8.63). Conclusion: These data strongly suggest that access to a regular source of health care and modification of lifestyle are important factors in the control of hypertension in the community.