A Dietary Intervention Study of Hypertension (DISH) was undertaken to determine whether patients whose high blood pressure had been controlled pharmacologically for a period of more than 5 years could maintain that control with sodium restriction or weight reduction instead of drugs. Four hundred ninety-six patients, classified by degree of overweight, were randomly assigned into one of seven groups. Included were those who would be withdrawn from antihypertensive medication and receive intervention for either sodium restriction or weight reduction. After 8 weeks of intervention, an average reduction of 24-hour urinary sodium output from a baseline of 158 mEq to 106 mEq (p less than .001) and from 130 mEq to 96 mEq (p less than .01) was achieved for the overweight and nonoverweight groups, respectively. That decline was still maintained at 56 weeks. Dietary estimates, obtained by analysis of 3-day food records, underestimated urinary output by an average of 12%, with blacks more likely to underestimate than whites, and the overweight more likely to underestimate than the nonoverweight. An average 10-lb weight loss was achieved, with no difference between men and women. Weight declined for 32 weeks, then leveled off and was maintained up to 56 weeks, indicating that sodium intake modification can be accomplished faster than weight reduction. Modest sodium restriction and weight reduction are feasible and achievable in a free-living population and have a positive effect on control of hypertension.