To examine the effect of modest dietary sodium ion restriction in treated hypertensive individuals, we studied 114 hypertensive patients undergoing individualized dietary counseling with a research dietitian to achieve reduction in dietary sodium ion intake. A significant reduction in mean sodium ion intake was achieved after the first of three lessons and was maintained for 30 weeks with no change in potassium ion intake. Significant falls in blood pressure and body weight were observed with no significant correlations noted between the two variables, implying independence of these effects. Individuals compliant with the dietary sodium ion restriction goal (urinary excretion, less than or equal to 80 mmol/d [less than or equal to 80 mEq/24 h]) were more likely to have a reduction in number of medications than those not reaching that goal. Ninety-eight of the 114 patients completed the entire 30 weeks. Patients who dropped out tended to have lower diastolic blood pressures and required fewer medications for blood pressure control than those who completed the 30 weeks. For these reasons, patients in the former group may have been less highly motivated to complete the study. These observations suggest that modest dietary sodium ion restriction is feasible in treated hypertensive patients and that adherence to such a regimen may permit blood pressure control with fewer medications.