Elevated blood pressure (BP) is a leading preventable cause of morbidity and mortality and an established independent risk factor for CVD and stroke. Fruit and vegetable-rich diets have been shown to reduce systolic blood pressure (SBP) in hypertensive subjects. Green leafy vegetables conferred the strongest protection. These contain high concentrations of nitrate that can act as a substrate for the endogenous formation of the potent vasodilator nitric oxide after consumption. Beetroot juice (BJ) is also rich in nitrate and has been shown to lower SBP by 10 mmHg in normotensive individuals when given as a 500 ml dose. The present study investigated the dose-response effects of BJ on 24 h ambulatory blood pressure (ABP). Twenty-five normotensive volunteers (18 males and 7 females), aged 18–64 years, consumed 3 doses of BJ (100, 250 and 500 ml) and a water/no BJ control in a single-blind, randomized and controlled crossover study. Low-nitrate mineral water was used to match the volume in all drinks to 500 ml. ABP was determined every 15 min for 1 h pre- and 4 h post-drink consumption, every 30 min for a further 9 h and hourly overnight. Urine was collected at 0, 2, 4, 6 and 24 h after BJ consumption. The subjects followed a low-nitrate diet for 48 h and consumed standardised low-nitrate meals the night before and during the study day.