High intake of fruits and vegetables is associated with reduced cardiovascular risk. A number of fruits and vegetables are rich in anthocyanins, which constitute a subgroup of the flavonoids. Anthocyanins have demonstrated anti-inflammatory and anti-oxidative properties, and anthocyanin-rich interventions have indicated beneficial effects on blood pressure and other cardiovascular risk factors. We assessed whether a purified anthocyanin supplement improves cardiovascular metabolic risk factors and markers of inflammation and oxidative stress in prehypertensive participants, and whether plasma polyphenols are increased 1-3 h following intake. In all, 31 men between 35-51 years with screening blood pressure >140/90 mm Hg without anti-hypertensive or lipid-lowering medication, were randomized in a double-blinded crossover study to placebo versus 640 mg anthocyanins daily. Treatment durations were 4 weeks with a 4-week washout. High-density lipoprotein (HDL)-cholesterol and blood glucose were significantly higher after anthocyanin versus placebo treatment (P=0.043 and P=0.024, respectively). No effects were observed on inflammation or oxidative stress in vivo, except for von Willebrand factor, which was higher in the anthocyanin period (P=0.007). Several plasma polyphenols increased significantly 1-3 h following anthocyanin intake. The present study strengthens the evidence that anthocyanins may increase HDL-cholesterol levels, and this is demonstrated for the first time in prehypertensive and non-dyslipidemic men. However, no other beneficial effects in the short term were found on pathophysiological markers of cardiovascular disease.