The anti- and pro-oxidant activity of water soluble components in Cichorium intybus var. silvestre was investigated. This vegetable is domestically known as Treviso red chicory recalling its cultivation in the area of Treviso (Italy). The vegetable juices, obtained by centrifugation of the vegetable and treated at 2 and 102 8C, were assessed for their antioxidant activity (AA) using the micellar model system linoleic acid/b-carotene. The obtained juice at 2 8C possessed either anti- or pro-oxidant activity. The boiled juice showed only strong AA, proving that the vegetable prooxidant components were thermally instable. Juice components were fractionated by sequential dialysis (1000/300 000 Da membrane cut-off), SPE, GFC, and RP-HPLC techniques showing the presence of several highly antioxidant components with different molecular weight (MW), and polar features in Treviso red chicory. The pro-oxidant fraction capable of masking the presence of the antioxidant components in the vegetable juice is retained by aMW higer than 300 000 Da dialysis membrane.