The health benefit of fruit juices have been ascribed, in part, to phenolic antioxidants. The antioxidant potential of a range of fruit juices was assessed by measurement of their ability to reduce a synthetic free radical, potassium nitrosodisulphonate, and also by their ability to reduce Fe(III). Vitamin C was found to account for 65-100% of the antioxidant potential of beverages derived from citrus fruit but less than 5% of apple and pineapple juice. The contribution of carotenoids to antioxidant potential was negligible. Although phenolics appear to be major contributors to the antioxidant potential of the non-citrus juices, their identity and bio-availability requires further investigation.