Blood pressure (BP) shows a continuous relationship with the risk of CVD. There is substantial evidence that dietary potassium exerts an anti-pressor effect. Most clinical trials have used KCl. However, the chloride ion may have a pressor effect and in foods potassium is associated with organic anions. In a double-blind randomized placebo-controlled trial we explored the effect on BP of two salts of potassium, KCl and potassium citrate (K-cit), in predominantly young healthy normotensive volunteers. The primary outcome was the change in mean arterial pressure as measured in a clinic setting. After 6 weeks of supplementation, compared with the placebo group (n 31), 30 mmol K-cit/d (n 28) changed mean arterial pressure by − 5·22 mmHg (95 % CI − 8·85, − 4·53) which did not differ significantly from that induced by KCl (n 26), − 4·70 mmHg ( − 6·56, − 2·84). The changes in systolic and diastolic BP were − 6·69 (95 % CI − 8·85, − 4·43) and − 4·26 (95 % CI − 6·31, − 2·21) mmHg with K-cit and − 5·24 (95 % CI − 7·43, − 3·06) and − 4·30 (95 % CI − 6·39, − 2·20) mmHg with KCl, and did not differ significantly between the two treatments. Changes in BP were not related to baseline urinary electrolytes. A greater treatment-related effect was observed in those with higher systolic BP. Increasing dietary potassium could therefore have a significant impact on the progressive rise in BP in the entire population.