The study sample consisted of 16,095 adults who were at least 25 years old and for whom blood-pressure values were known. We estimated that 27 percent of the population had hypertension, but only 23 percent of those with hypertension were taking medications that controlled their condition. Among subjects with untreated or uncontrolled hypertension, the pattern was an elevation in the systolic blood pressure with a diastolic pressure of less than 90 mm Hg. The great majority had health insurance. Independent predictors of a lack of awareness of hypertension were an age of at least 65 years, male sex, non-Hispanic black race, and not having visited a physician within the preceding 12 months. The same variables, except for non-Hispanic black race, were independently associated with poor control of hypertension among those who were aware of their condition. An age of at least 65 years accounted for the greatest proportion of the attributable risk of the lack of awareness of hypertension and the lack of control of hypertension among those who were aware of their condition