Randomized, double-blind. One hundred forty-five subjects were randomized into a low sodium placebo group in which sodium intake was restricted to no more than 80 mEq/day, 142 subjects into a potassium supplementation (96 mEq/day) group whose sodium intake was also restricted to no more than 80 mEq/day. After 12 weeks of intervention, antihypertensive drugs were withdrawn. Follow-up of each participant was for at least two years. The primary endpoint was the proportion of subjects requiring antihypertensive medication at various points following randomization.