The Trial of Antihypertensive Interventions and Management (TAIM) was a multicenter randomized drug (double-blind, placebo-controlled)-diet trial. One objective of TAIM was to assess the long-term ability of a low-sodium/high-potassium (Na+ decreases/K+ increases) diet to maintain blood pressure control in persons at 110% to 160% ideal weight with diastolic blood pressure from 90 to 100 mm Hg who were on no drugs or on low-dose monotherapy. Participants, 56% men and 33% black, were randomized to usual diet (n = 296) or to Na+ decreases/K+ increases diet (n = 291) and within each diet group to placebo, 25 mg/day chlorthalidone, or 50 mg/day atenolol. Treatment failure was defined as lack of blood pressure control requiring additional drugs according to specified criteria. At baseline, the mean value for age was 48 years; blood pressure, 143/93 mm Hg; weight, 88 kg; and 24-h urinary sodium and potassium excretion rates, 133 and 57 mmol/day, respectively. At 3 years, the net difference in 24-h urinary sodium/potassium excretion rates between the Na+ decreases/K+ increases and the usual diet groups was -30 and +11 mmol/L/day. The relative risk of treatment failure for Na+ decreases/K+ increases compared to usual diet by proportional hazards regression was 0.95 (P = .71). This study provides no support for the sole use of a low-sodium/high-potassium diet as a practical therapeutic strategy in maintaining blood pressure control in the moderately obese.